diff --git a/src/main/java/com/android/tools/r8/BackportedMethodListCommand.java b/src/main/java/com/android/tools/r8/BackportedMethodListCommand.java
index 61caf95..bce73f0 100644
--- a/src/main/java/com/android/tools/r8/BackportedMethodListCommand.java
+++ b/src/main/java/com/android/tools/r8/BackportedMethodListCommand.java
@@ -4,8 +4,8 @@
 package com.android.tools.r8;
 
 import com.android.tools.r8.graph.DexItemFactory;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfigurationParser;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecificationParser;
 import com.android.tools.r8.origin.Origin;
 import com.android.tools.r8.utils.AndroidApiLevel;
 import com.android.tools.r8.utils.AndroidApp;
@@ -41,7 +41,7 @@
   private final boolean printVersion;
   private final Reporter reporter;
   private final int minApiLevel;
-  private final DesugaredLibraryConfiguration desugaredLibraryConfiguration;
+  private final LegacyDesugaredLibrarySpecification desugaredLibrarySpecification;
   private final AndroidApp app;
   private final StringConsumer backportedMethodListConsumer;
   private final DexItemFactory factory;
@@ -62,8 +62,8 @@
     return minApiLevel;
   }
 
-  public DesugaredLibraryConfiguration getDesugaredLibraryConfiguration() {
-    return desugaredLibraryConfiguration;
+  public LegacyDesugaredLibrarySpecification getDesugaredLibraryConfiguration() {
+    return desugaredLibrarySpecification;
   }
 
   public StringConsumer getBackportedMethodListConsumer() {
@@ -79,7 +79,7 @@
     this.printVersion = printVersion;
     this.reporter = new Reporter();
     this.minApiLevel = -1;
-    this.desugaredLibraryConfiguration = null;
+    this.desugaredLibrarySpecification = null;
     this.app = null;
     this.backportedMethodListConsumer = null;
     this.factory = null;
@@ -88,7 +88,7 @@
   private BackportedMethodListCommand(
       Reporter reporter,
       int minApiLevel,
-      DesugaredLibraryConfiguration desugaredLibraryConfiguration,
+      LegacyDesugaredLibrarySpecification desugaredLibrarySpecification,
       AndroidApp app,
       StringConsumer backportedMethodListConsumer,
       DexItemFactory factory) {
@@ -96,7 +96,7 @@
     this.printVersion = false;
     this.reporter = reporter;
     this.minApiLevel = minApiLevel;
-    this.desugaredLibraryConfiguration = desugaredLibraryConfiguration;
+    this.desugaredLibrarySpecification = desugaredLibrarySpecification;
     this.app = app;
     this.backportedMethodListConsumer = backportedMethodListConsumer;
     this.factory = factory;
@@ -105,7 +105,7 @@
   InternalOptions getInternalOptions() {
     InternalOptions options = new InternalOptions(factory, getReporter());
     options.setMinApiLevel(AndroidApiLevel.getAndroidApiLevel(minApiLevel));
-    options.desugaredLibraryConfiguration = desugaredLibraryConfiguration;
+    options.desugaredLibrarySpecification = desugaredLibrarySpecification;
     return options;
   }
 
@@ -178,7 +178,7 @@
 
     private final Reporter reporter;
     private int minApiLevel = AndroidApiLevel.B.getLevel();
-    private List<StringResource> desugaredLibraryConfigurationResources = new ArrayList<>();
+    private List<StringResource> desugaredLibrarySpecificationResources = new ArrayList<>();
     private final AndroidApp.Builder app;
     private StringConsumer backportedMethodListConsumer;
     private boolean printHelp = false;
@@ -215,7 +215,7 @@
 
     /** Desugared library configuration */
     public Builder addDesugaredLibraryConfiguration(StringResource configuration) {
-      desugaredLibraryConfigurationResources.add(configuration);
+      desugaredLibrarySpecificationResources.add(configuration);
       return this;
     }
 
@@ -245,18 +245,18 @@
       return this;
     }
 
-    DesugaredLibraryConfiguration getDesugaredLibraryConfiguration(DexItemFactory factory) {
-      if (desugaredLibraryConfigurationResources.isEmpty()) {
-        return DesugaredLibraryConfiguration.empty();
+    LegacyDesugaredLibrarySpecification getDesugaredLibraryConfiguration(DexItemFactory factory) {
+      if (desugaredLibrarySpecificationResources.isEmpty()) {
+        return LegacyDesugaredLibrarySpecification.empty();
       }
-      if (desugaredLibraryConfigurationResources.size() > 1) {
+      if (desugaredLibrarySpecificationResources.size() > 1) {
         reporter.fatalError("Only one desugared library configuration is supported.");
       }
-      StringResource desugaredLibraryConfigurationResource =
-          desugaredLibraryConfigurationResources.get(0);
-      DesugaredLibraryConfigurationParser libraryParser =
-          new DesugaredLibraryConfigurationParser(factory, null, false, getMinApiLevel());
-      return libraryParser.parse(desugaredLibraryConfigurationResource);
+      StringResource desugaredLibrarySpecificationResource =
+          desugaredLibrarySpecificationResources.get(0);
+      LegacyDesugaredLibrarySpecificationParser libraryParser =
+          new LegacyDesugaredLibrarySpecificationParser(factory, null, false, getMinApiLevel());
+      return libraryParser.parse(desugaredLibrarySpecificationResource);
     }
 
     /** Output file for the backported method list */
@@ -306,7 +306,7 @@
 
     public BackportedMethodListCommand build() {
       AndroidApp library = app.build();
-      if (!desugaredLibraryConfigurationResources.isEmpty()
+      if (!desugaredLibrarySpecificationResources.isEmpty()
           && library.getLibraryResourceProviders().isEmpty()) {
         reporter.error(
             new StringDiagnostic("With desugared library configuration a library is required"));
diff --git a/src/main/java/com/android/tools/r8/BaseCompilerCommand.java b/src/main/java/com/android/tools/r8/BaseCompilerCommand.java
index 4af2547..18b7c02 100644
--- a/src/main/java/com/android/tools/r8/BaseCompilerCommand.java
+++ b/src/main/java/com/android/tools/r8/BaseCompilerCommand.java
@@ -7,8 +7,8 @@
 import com.android.tools.r8.errors.Unreachable;
 import com.android.tools.r8.graph.DexItemFactory;
 import com.android.tools.r8.inspector.Inspector;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfigurationParser;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecificationParser;
 import com.android.tools.r8.origin.Origin;
 import com.android.tools.r8.utils.AndroidApiLevel;
 import com.android.tools.r8.utils.AndroidApp;
@@ -224,7 +224,7 @@
     private int minApiLevel = 0;
     private int threadCount = ThreadUtils.NOT_SPECIFIED;
     protected DesugarState desugarState = DesugarState.ON;
-    private List<StringResource> desugaredLibraryConfigurationResources = new ArrayList<>();
+    private List<StringResource> desugaredLibrarySpecificationResources = new ArrayList<>();
     private boolean includeClassesChecksum = false;
     private boolean lookupLibraryBeforeProgram = true;
     private boolean optimizeMultidexForLinearAlloc = false;
@@ -562,35 +562,35 @@
     /** Desugared library configuration */
     // Configuration "default" is for testing only and support will be dropped.
     public B addDesugaredLibraryConfiguration(String configuration) {
-      this.desugaredLibraryConfigurationResources.add(
+      this.desugaredLibrarySpecificationResources.add(
           StringResource.fromString(configuration, Origin.unknown()));
       return self();
     }
 
     /** Desugared library configuration */
     public B addDesugaredLibraryConfiguration(StringResource configuration) {
-      this.desugaredLibraryConfigurationResources.add(configuration);
+      this.desugaredLibrarySpecificationResources.add(configuration);
       return self();
     }
 
-    DesugaredLibraryConfiguration getDesugaredLibraryConfiguration(
+    LegacyDesugaredLibrarySpecification getDesugaredLibraryConfiguration(
         DexItemFactory factory, boolean libraryCompilation) {
-      if (desugaredLibraryConfigurationResources.isEmpty()) {
-        return DesugaredLibraryConfiguration.empty();
+      if (desugaredLibrarySpecificationResources.isEmpty()) {
+        return LegacyDesugaredLibrarySpecification.empty();
       }
-      if (desugaredLibraryConfigurationResources.size() > 1) {
+      if (desugaredLibrarySpecificationResources.size() > 1) {
         throw new CompilationError("Only one desugared library configuration is supported.");
       }
-      StringResource desugaredLibraryConfigurationResource =
-          desugaredLibraryConfigurationResources.get(0);
-      DesugaredLibraryConfigurationParser libraryParser =
-          new DesugaredLibraryConfigurationParser(
+      StringResource desugaredLibrarySpecificationResource =
+          desugaredLibrarySpecificationResources.get(0);
+      LegacyDesugaredLibrarySpecificationParser libraryParser =
+          new LegacyDesugaredLibrarySpecificationParser(
               factory, getReporter(), libraryCompilation, getMinApiLevel());
-      return libraryParser.parse(desugaredLibraryConfigurationResource);
+      return libraryParser.parse(desugaredLibrarySpecificationResource);
     }
 
     boolean hasDesugaredLibraryConfiguration() {
-      return !desugaredLibraryConfigurationResources.isEmpty();
+      return !desugaredLibrarySpecificationResources.isEmpty();
     }
 
     /** Encodes checksum for each class when generating dex files. */
diff --git a/src/main/java/com/android/tools/r8/D8.java b/src/main/java/com/android/tools/r8/D8.java
index c7240f8..3b3e48e 100644
--- a/src/main/java/com/android/tools/r8/D8.java
+++ b/src/main/java/com/android/tools/r8/D8.java
@@ -169,7 +169,7 @@
       AndroidApp inputApp, InternalOptions options, ExecutorService executor, Timing timing)
       throws IOException {
     PrefixRewritingMapper rewritePrefix =
-        options.desugaredLibraryConfiguration.getPrefixRewritingMapper();
+        options.desugaredLibrarySpecification.getPrefixRewritingMapper();
     ApplicationReader applicationReader = new ApplicationReader(inputApp, options, timing);
     LazyLoadedDexApplication app = applicationReader.read(executor);
     AppInfo appInfo = AppInfo.createInitialAppInfo(app, applicationReader.readMainDexClasses(app));
diff --git a/src/main/java/com/android/tools/r8/D8Command.java b/src/main/java/com/android/tools/r8/D8Command.java
index 8d0f357..d667575 100644
--- a/src/main/java/com/android/tools/r8/D8Command.java
+++ b/src/main/java/com/android/tools/r8/D8Command.java
@@ -12,7 +12,7 @@
 import com.android.tools.r8.horizontalclassmerging.HorizontalClassMerger;
 import com.android.tools.r8.inspector.Inspector;
 import com.android.tools.r8.inspector.internal.InspectorImpl;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
 import com.android.tools.r8.origin.Origin;
 import com.android.tools.r8.shaking.ProguardConfigurationParser;
 import com.android.tools.r8.shaking.ProguardConfigurationRule;
@@ -288,7 +288,7 @@
       intermediate |= getProgramConsumer() instanceof DexFilePerClassFileConsumer;
 
       DexItemFactory factory = new DexItemFactory();
-      DesugaredLibraryConfiguration libraryConfiguration =
+      LegacyDesugaredLibrarySpecification desugaredLibrarySpecification =
           getDesugaredLibraryConfiguration(factory, false);
 
       ImmutableList<ProguardConfigurationRule> mainDexKeepRules =
@@ -308,7 +308,7 @@
           getDexClassChecksumFilter(),
           getDesugarGraphConsumer(),
           desugaredLibraryKeepRuleConsumer,
-          libraryConfiguration,
+          desugaredLibrarySpecification,
           getAssertionsConfiguration(),
           getOutputInspections(),
           synthesizedClassPrefix,
@@ -328,7 +328,7 @@
   private final boolean intermediate;
   private final DesugarGraphConsumer desugarGraphConsumer;
   private final StringConsumer desugaredLibraryKeepRuleConsumer;
-  private final DesugaredLibraryConfiguration libraryConfiguration;
+  private final LegacyDesugaredLibrarySpecification desugaredLibrarySpecification;
   private final String synthesizedClassPrefix;
   private final boolean skipDump;
   private final boolean enableMainDexListCheck;
@@ -390,7 +390,7 @@
       BiPredicate<String, Long> dexClassChecksumFilter,
       DesugarGraphConsumer desugarGraphConsumer,
       StringConsumer desugaredLibraryKeepRuleConsumer,
-      DesugaredLibraryConfiguration libraryConfiguration,
+      LegacyDesugaredLibrarySpecification desugaredLibrarySpecification,
       List<AssertionsConfiguration> assertionsConfiguration,
       List<Consumer<Inspector>> outputInspections,
       String synthesizedClassPrefix,
@@ -422,7 +422,7 @@
     this.intermediate = intermediate;
     this.desugarGraphConsumer = desugarGraphConsumer;
     this.desugaredLibraryKeepRuleConsumer = desugaredLibraryKeepRuleConsumer;
-    this.libraryConfiguration = libraryConfiguration;
+    this.desugaredLibrarySpecification = desugaredLibrarySpecification;
     this.synthesizedClassPrefix = synthesizedClassPrefix;
     this.skipDump = skipDump;
     this.enableMainDexListCheck = enableMainDexListCheck;
@@ -436,7 +436,7 @@
     intermediate = false;
     desugarGraphConsumer = null;
     desugaredLibraryKeepRuleConsumer = null;
-    libraryConfiguration = null;
+    desugaredLibrarySpecification = null;
     synthesizedClassPrefix = null;
     skipDump = false;
     enableMainDexListCheck = true;
@@ -500,7 +500,7 @@
     internal.dexClassChecksumFilter = getDexClassChecksumFilter();
     internal.enableInheritanceClassInDexDistributor = isOptimizeMultidexForLinearAlloc();
 
-    internal.desugaredLibraryConfiguration = libraryConfiguration;
+    internal.desugaredLibrarySpecification = desugaredLibrarySpecification;
     internal.synthesizedClassPrefix = synthesizedClassPrefix;
     internal.desugaredLibraryKeepRuleConsumer = desugaredLibraryKeepRuleConsumer;
 
@@ -528,7 +528,7 @@
     dumpBaseCommandOptions(builder);
     return builder
         .setIntermediate(intermediate)
-        .setDesugaredLibraryConfiguration(libraryConfiguration)
+        .setDesugaredLibraryConfiguration(desugaredLibrarySpecification)
         .setMainDexKeepRules(mainDexKeepRules)
         .build();
   }
diff --git a/src/main/java/com/android/tools/r8/DumpOptions.java b/src/main/java/com/android/tools/r8/DumpOptions.java
index 14ae9c6..c7f3345 100644
--- a/src/main/java/com/android/tools/r8/DumpOptions.java
+++ b/src/main/java/com/android/tools/r8/DumpOptions.java
@@ -7,7 +7,7 @@
 import com.android.tools.r8.dex.Marker.Tool;
 import com.android.tools.r8.experimental.startup.StartupConfiguration;
 import com.android.tools.r8.features.FeatureSplitConfiguration;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
 import com.android.tools.r8.shaking.ProguardConfiguration;
 import com.android.tools.r8.shaking.ProguardConfigurationRule;
 import com.android.tools.r8.utils.InternalOptions.DesugarState;
@@ -50,7 +50,7 @@
   private final Optional<Boolean> forceProguardCompatibility;
 
   // Dump if present.
-  private final DesugaredLibraryConfiguration desugaredLibraryConfiguration;
+  private final LegacyDesugaredLibrarySpecification desugaredLibrarySpecification;
   private final FeatureSplitConfiguration featureSplitConfiguration;
   private final ProguardConfiguration proguardConfiguration;
   private final List<ProguardConfigurationRule> mainDexKeepRules;
@@ -62,7 +62,7 @@
       Tool tool,
       CompilationMode compilationMode,
       int minAPI,
-      DesugaredLibraryConfiguration desugaredLibraryConfiguration,
+      LegacyDesugaredLibrarySpecification desugaredLibrarySpecification,
       boolean optimizeMultidexForLinearAlloc,
       int threadCount,
       DesugarState desugarState,
@@ -78,7 +78,7 @@
     this.tool = tool;
     this.compilationMode = compilationMode;
     this.minApi = minAPI;
-    this.desugaredLibraryConfiguration = desugaredLibraryConfiguration;
+    this.desugaredLibrarySpecification = desugaredLibrarySpecification;
     this.optimizeMultidexForLinearAlloc = optimizeMultidexForLinearAlloc;
     this.threadCount = threadCount;
     this.desugarState = desugarState;
@@ -133,13 +133,13 @@
   }
 
   private boolean hasDesugaredLibraryConfiguration() {
-    return desugaredLibraryConfiguration != null
-        && !desugaredLibraryConfiguration.isEmptyConfiguration();
+    return desugaredLibrarySpecification != null
+        && !desugaredLibrarySpecification.isEmptyConfiguration();
   }
 
   public String getDesugaredLibraryJsonSource() {
     if (hasDesugaredLibraryConfiguration()) {
-      return desugaredLibraryConfiguration.getJsonSource();
+      return desugaredLibrarySpecification.getJsonSource();
     }
     return null;
   }
@@ -186,7 +186,7 @@
     private Optional<Boolean> minification = Optional.empty();
     private Optional<Boolean> forceProguardCompatibility = Optional.empty();
     // Dump if present.
-    private DesugaredLibraryConfiguration desugaredLibraryConfiguration;
+    private LegacyDesugaredLibrarySpecification desugaredLibrarySpecification;
     private FeatureSplitConfiguration featureSplitConfiguration;
     private ProguardConfiguration proguardConfiguration;
     private List<ProguardConfigurationRule> mainDexKeepRules;
@@ -209,8 +209,8 @@
     }
 
     public Builder setDesugaredLibraryConfiguration(
-        DesugaredLibraryConfiguration desugaredLibraryConfiguration) {
-      this.desugaredLibraryConfiguration = desugaredLibraryConfiguration;
+        LegacyDesugaredLibrarySpecification desugaredLibrarySpecification) {
+      this.desugaredLibrarySpecification = desugaredLibrarySpecification;
       return this;
     }
 
@@ -280,7 +280,7 @@
           tool,
           compilationMode,
           minApi,
-          desugaredLibraryConfiguration,
+          desugaredLibrarySpecification,
           optimizeMultidexForLinearAlloc,
           threadCount,
           desugarState,
diff --git a/src/main/java/com/android/tools/r8/GenerateLintFiles.java b/src/main/java/com/android/tools/r8/GenerateLintFiles.java
index cde20fa..660b1ef 100644
--- a/src/main/java/com/android/tools/r8/GenerateLintFiles.java
+++ b/src/main/java/com/android/tools/r8/GenerateLintFiles.java
@@ -34,8 +34,8 @@
 import com.android.tools.r8.graph.LazyLoadedDexApplication;
 import com.android.tools.r8.graph.MethodAccessFlags;
 import com.android.tools.r8.graph.ProgramMethod;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfigurationParser;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecificationParser;
 import com.android.tools.r8.jar.CfApplicationWriter;
 import com.android.tools.r8.naming.NamingLens;
 import com.android.tools.r8.origin.Origin;
@@ -73,7 +73,7 @@
   private final Reporter reporter = new Reporter();
   private final InternalOptions options = new InternalOptions(factory, reporter);
 
-  private final DesugaredLibraryConfiguration desugaredLibraryConfiguration;
+  private final LegacyDesugaredLibrarySpecification desugaredLibrarySpecification;
   private final Path desugaredLibraryImplementation;
   private final Path outputDirectory;
 
@@ -82,7 +82,7 @@
   public GenerateLintFiles(
       String desugarConfigurationPath, String desugarImplementationPath, String outputDirectory)
       throws Exception {
-    this.desugaredLibraryConfiguration =
+    this.desugaredLibrarySpecification =
         readDesugaredLibraryConfiguration(desugarConfigurationPath);
     this.desugaredLibraryImplementation = Paths.get(desugarImplementationPath);
     this.outputDirectory = Paths.get(outputDirectory);
@@ -119,9 +119,9 @@
     return Paths.get(jar);
   }
 
-  private DesugaredLibraryConfiguration readDesugaredLibraryConfiguration(
+  private LegacyDesugaredLibrarySpecification readDesugaredLibraryConfiguration(
       String desugarConfigurationPath) {
-    return new DesugaredLibraryConfigurationParser(
+    return new LegacyDesugaredLibrarySpecificationParser(
             factory, reporter, false, AndroidApiLevel.B.getLevel())
         .parse(StringResource.fromFile(Paths.get(desugarConfigurationPath)));
   }
@@ -230,7 +230,7 @@
     for (DexProgramClass clazz : dexApplication.classes()) {
       String className = clazz.toSourceString();
       // All the methods with the rewritten prefix are supported.
-      for (String prefix : desugaredLibraryConfiguration.getRewritePrefix().keySet()) {
+      for (String prefix : desugaredLibrarySpecification.getRewritePrefix().keySet()) {
         if (clazz.accessFlags.isPublic() && className.startsWith(prefix)) {
           DexProgramClass implementationClass =
               implementationApplication.programDefinitionFor(clazz.getType());
@@ -259,11 +259,11 @@
 
       // All retargeted methods are supported.
       for (DexEncodedMethod method : clazz.methods()) {
-        if (desugaredLibraryConfiguration
+        if (desugaredLibrarySpecification
             .getRetargetCoreLibMember()
             .keySet()
             .contains(method.getReference().name)) {
-          if (desugaredLibraryConfiguration
+          if (desugaredLibrarySpecification
               .getRetargetCoreLibMember()
               .get(method.getReference().name)
               .containsKey(clazz.type)) {
@@ -275,7 +275,7 @@
       }
 
       // All emulated interfaces static and default methods are supported.
-      if (desugaredLibraryConfiguration.getEmulateLibraryInterface().containsKey(clazz.type)) {
+      if (desugaredLibrarySpecification.getEmulateLibraryInterface().containsKey(clazz.type)) {
         assert clazz.isInterface();
         for (DexEncodedMethod method : clazz.methods()) {
           if (!method.isDefaultMethod() && !method.isStatic()) {
@@ -384,7 +384,7 @@
   private void run() throws Exception {
     // Run over all the API levels that the desugared library can be compiled with.
     for (int apiLevel = AndroidApiLevel.LATEST.getLevel();
-        apiLevel >= desugaredLibraryConfiguration.getRequiredCompilationApiLevel().getLevel();
+        apiLevel >= desugaredLibrarySpecification.getRequiredCompilationApiLevel().getLevel();
         apiLevel--) {
       System.out.println("Generating lint files for compile API " + apiLevel);
       run(apiLevel);
diff --git a/src/main/java/com/android/tools/r8/L8.java b/src/main/java/com/android/tools/r8/L8.java
index 318a055..c68fc77 100644
--- a/src/main/java/com/android/tools/r8/L8.java
+++ b/src/main/java/com/android/tools/r8/L8.java
@@ -162,7 +162,7 @@
         new ApplicationReader(inputApp, options, timing).read(executor);
 
     PrefixRewritingMapper rewritePrefix =
-        options.desugaredLibraryConfiguration.getPrefixRewritingMapper();
+        options.desugaredLibrarySpecification.getPrefixRewritingMapper();
 
     DexApplication app = new L8TreePruner(options).prune(lazyApp, rewritePrefix);
     return AppView.createForL8(AppInfo.createInitialAppInfo(app), rewritePrefix);
diff --git a/src/main/java/com/android/tools/r8/L8Command.java b/src/main/java/com/android/tools/r8/L8Command.java
index 51ea781..c39a041 100644
--- a/src/main/java/com/android/tools/r8/L8Command.java
+++ b/src/main/java/com/android/tools/r8/L8Command.java
@@ -12,7 +12,7 @@
 import com.android.tools.r8.graph.DexItemFactory;
 import com.android.tools.r8.horizontalclassmerging.HorizontalClassMerger;
 import com.android.tools.r8.inspector.Inspector;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
 import com.android.tools.r8.origin.Origin;
 import com.android.tools.r8.utils.AndroidApiLevel;
 import com.android.tools.r8.utils.AndroidApp;
@@ -42,7 +42,7 @@
 
   private final D8Command d8Command;
   private final R8Command r8Command;
-  private final DesugaredLibraryConfiguration libraryConfiguration;
+  private final LegacyDesugaredLibrarySpecification desugaredLibrarySpecification;
   private final DexItemFactory factory;
 
   boolean isShrinking() {
@@ -95,7 +95,7 @@
       Reporter diagnosticsHandler,
       boolean encodeChecksum,
       BiPredicate<String, Long> dexClassChecksumFilter,
-      DesugaredLibraryConfiguration libraryConfiguration,
+      LegacyDesugaredLibrarySpecification desugaredLibrarySpecification,
       List<AssertionsConfiguration> assertionsConfiguration,
       List<Consumer<Inspector>> outputInspections,
       int threadCount,
@@ -121,7 +121,7 @@
         null);
     this.d8Command = d8Command;
     this.r8Command = r8Command;
-    this.libraryConfiguration = libraryConfiguration;
+    this.desugaredLibrarySpecification = desugaredLibrarySpecification;
     this.factory = factory;
   }
 
@@ -129,7 +129,7 @@
     super(printHelp, printVersion);
     r8Command = null;
     d8Command = null;
-    libraryConfiguration = null;
+    desugaredLibrarySpecification = null;
     factory = null;
   }
 
@@ -194,10 +194,10 @@
     assert internal.enableInheritanceClassInDexDistributor;
     internal.enableInheritanceClassInDexDistributor = false;
 
-    assert libraryConfiguration != null;
-    internal.desugaredLibraryConfiguration = libraryConfiguration;
+    assert desugaredLibrarySpecification != null;
+    internal.desugaredLibrarySpecification = desugaredLibrarySpecification;
     internal.synthesizedClassPrefix =
-        libraryConfiguration.getSynthesizedLibraryClassesPackagePrefix();
+        desugaredLibrarySpecification.getSynthesizedLibraryClassesPackagePrefix();
 
     // Default is to remove all javac generated assertion code when generating dex.
     assert internal.assertionsConfiguration == null;
@@ -332,7 +332,7 @@
       }
 
       DexItemFactory factory = new DexItemFactory();
-      DesugaredLibraryConfiguration libraryConfiguration =
+      LegacyDesugaredLibrarySpecification desugaredLibrarySpecification =
           getDesugaredLibraryConfiguration(factory, true);
 
       R8Command r8Command = null;
@@ -346,7 +346,7 @@
             R8Command.builder(getReporter())
                 .addProgramResourceProvider((ProgramResourceProvider) l8CfConsumer)
                 .setSynthesizedClassesPrefix(
-                    libraryConfiguration.getSynthesizedLibraryClassesPackagePrefix())
+                    desugaredLibrarySpecification.getSynthesizedLibraryClassesPackagePrefix())
                 .setMinApiLevel(getMinApiLevel())
                 .setMode(getMode())
                 .setIncludeClassesChecksum(getIncludeClassesChecksum())
@@ -363,7 +363,7 @@
           r8Builder.setProguardMapConsumer(proguardMapConsumer);
         }
         r8Builder.addProguardConfiguration(
-            libraryConfiguration.getExtraKeepRules(), Origin.unknown());
+            desugaredLibrarySpecification.getExtraKeepRules(), Origin.unknown());
         // TODO(b/180903899): Remove rule when -dontwarn sun.misc.Unsafe is part of config.
         r8Builder.addProguardConfiguration(
             ImmutableList.of("-dontwarn sun.misc.Unsafe"), Origin.unknown());
@@ -377,7 +377,7 @@
             D8Command.builder(getReporter())
                 .addProgramResourceProvider((ProgramResourceProvider) l8CfConsumer)
                 .setSynthesizedClassesPrefix(
-                    libraryConfiguration.getSynthesizedLibraryClassesPackagePrefix())
+                    desugaredLibrarySpecification.getSynthesizedLibraryClassesPackagePrefix())
                 .setMinApiLevel(getMinApiLevel())
                 .setMode(getMode())
                 .setIncludeClassesChecksum(getIncludeClassesChecksum())
@@ -406,7 +406,7 @@
           getReporter(),
           getIncludeClassesChecksum(),
           getDexClassChecksumFilter(),
-          libraryConfiguration,
+          desugaredLibrarySpecification,
           getAssertionsConfiguration(),
           getOutputInspections(),
           getThreadCount(),
@@ -444,6 +444,6 @@
     if (r8Command != null) {
       builder.setProguardConfiguration(r8Command.getInternalOptions().getProguardConfiguration());
     }
-    return builder.setDesugaredLibraryConfiguration(libraryConfiguration).build();
+    return builder.setDesugaredLibraryConfiguration(desugaredLibrarySpecification).build();
   }
 }
diff --git a/src/main/java/com/android/tools/r8/R8.java b/src/main/java/com/android/tools/r8/R8.java
index cf83f78..b216f04 100644
--- a/src/main/java/com/android/tools/r8/R8.java
+++ b/src/main/java/com/android/tools/r8/R8.java
@@ -309,7 +309,7 @@
       if (!options.mainDexKeepRules.isEmpty()) {
         MainDexListBuilder.checkForAssumedLibraryTypes(appView.appInfo());
       }
-      if (!options.desugaredLibraryConfiguration.getRetargetCoreLibMember().isEmpty()) {
+      if (!options.desugaredLibrarySpecification.getRetargetCoreLibMember().isEmpty()) {
         DesugaredLibraryRetargeterLibraryTypeSynthesizer.checkForAssumedLibraryTypes(appView);
         DesugaredLibraryRetargeterLibraryTypeSynthesizer.amendLibraryWithRetargetedMembers(appView);
       }
diff --git a/src/main/java/com/android/tools/r8/R8Command.java b/src/main/java/com/android/tools/r8/R8Command.java
index 4b53393..b51ee2e 100644
--- a/src/main/java/com/android/tools/r8/R8Command.java
+++ b/src/main/java/com/android/tools/r8/R8Command.java
@@ -15,7 +15,7 @@
 import com.android.tools.r8.graph.DexItemFactory;
 import com.android.tools.r8.inspector.Inspector;
 import com.android.tools.r8.inspector.internal.InspectorImpl;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
 import com.android.tools.r8.naming.SourceFileRewriter;
 import com.android.tools.r8.origin.Origin;
 import com.android.tools.r8.origin.PathOrigin;
@@ -475,7 +475,7 @@
       List<ProguardConfigurationRule> mainDexKeepRules =
           ProguardConfigurationParser.parse(mainDexRules, factory, reporter);
 
-      DesugaredLibraryConfiguration libraryConfiguration =
+      LegacyDesugaredLibrarySpecification desugaredLibrarySpecification =
           getDesugaredLibraryConfiguration(factory, false);
 
       ProguardConfigurationParser parser =
@@ -585,7 +585,7 @@
               getIncludeClassesChecksum(),
               getDexClassChecksumFilter(),
               desugaredLibraryKeepRuleConsumer,
-              libraryConfiguration,
+              desugaredLibrarySpecification,
               featureSplitConfiguration,
               getAssertionsConfiguration(),
               getOutputInspections(),
@@ -669,7 +669,7 @@
   private final GraphConsumer mainDexKeptGraphConsumer;
   private final Consumer<List<ProguardConfigurationRule>> syntheticProguardRulesConsumer;
   private final StringConsumer desugaredLibraryKeepRuleConsumer;
-  private final DesugaredLibraryConfiguration libraryConfiguration;
+  private final LegacyDesugaredLibrarySpecification desugaredLibrarySpecification;
   private final FeatureSplitConfiguration featureSplitConfiguration;
   private final String synthesizedClassPrefix;
   private final boolean skipDump;
@@ -747,7 +747,7 @@
       boolean encodeChecksum,
       BiPredicate<String, Long> dexClassChecksumFilter,
       StringConsumer desugaredLibraryKeepRuleConsumer,
-      DesugaredLibraryConfiguration libraryConfiguration,
+      LegacyDesugaredLibrarySpecification desugaredLibrarySpecification,
       FeatureSplitConfiguration featureSplitConfiguration,
       List<AssertionsConfiguration> assertionsConfiguration,
       List<Consumer<Inspector>> outputInspections,
@@ -791,7 +791,7 @@
     this.mainDexKeptGraphConsumer = mainDexKeptGraphConsumer;
     this.syntheticProguardRulesConsumer = syntheticProguardRulesConsumer;
     this.desugaredLibraryKeepRuleConsumer = desugaredLibraryKeepRuleConsumer;
-    this.libraryConfiguration = libraryConfiguration;
+    this.desugaredLibrarySpecification = desugaredLibrarySpecification;
     this.featureSplitConfiguration = featureSplitConfiguration;
     this.synthesizedClassPrefix = synthesizedClassPrefix;
     this.skipDump = skipDump;
@@ -814,7 +814,7 @@
     mainDexKeptGraphConsumer = null;
     syntheticProguardRulesConsumer = null;
     desugaredLibraryKeepRuleConsumer = null;
-    libraryConfiguration = null;
+    desugaredLibrarySpecification = null;
     featureSplitConfiguration = null;
     synthesizedClassPrefix = null;
     skipDump = false;
@@ -942,7 +942,7 @@
 
     internal.enableInheritanceClassInDexDistributor = isOptimizeMultidexForLinearAlloc();
 
-    internal.desugaredLibraryConfiguration = libraryConfiguration;
+    internal.desugaredLibrarySpecification = desugaredLibrarySpecification;
     internal.synthesizedClassPrefix = synthesizedClassPrefix;
     internal.desugaredLibraryKeepRuleConsumer = desugaredLibraryKeepRuleConsumer;
 
@@ -1000,7 +1000,7 @@
         .setFeatureSplitConfiguration(featureSplitConfiguration)
         .setProguardConfiguration(proguardConfiguration)
         .setMainDexKeepRules(mainDexKeepRules)
-        .setDesugaredLibraryConfiguration(libraryConfiguration)
+        .setDesugaredLibraryConfiguration(desugaredLibrarySpecification)
         .build();
   }
 }
diff --git a/src/main/java/com/android/tools/r8/androidapi/AndroidApiReferenceLevelCache.java b/src/main/java/com/android/tools/r8/androidapi/AndroidApiReferenceLevelCache.java
index 27fbc38..b4609ce 100644
--- a/src/main/java/com/android/tools/r8/androidapi/AndroidApiReferenceLevelCache.java
+++ b/src/main/java/com/android/tools/r8/androidapi/AndroidApiReferenceLevelCache.java
@@ -9,14 +9,14 @@
 import com.android.tools.r8.graph.DexItemFactory;
 import com.android.tools.r8.graph.DexReference;
 import com.android.tools.r8.graph.DexType;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
 import com.android.tools.r8.utils.AndroidApiLevel;
 import com.google.common.collect.ImmutableList;
 import java.util.List;
 
 public class AndroidApiReferenceLevelCache {
 
-  private final DesugaredLibraryConfiguration desugaredLibraryConfiguration;
+  private final LegacyDesugaredLibrarySpecification desugaredLibrarySpecification;
   private final AndroidApiLevelCompute apiLevelCompute;
   private final AndroidApiLevelDatabase androidApiLevelDatabase;
   private final AppView<?> appView;
@@ -31,7 +31,7 @@
     factory = appView.dexItemFactory();
     androidApiLevelDatabase =
         new AndroidApiLevelHashingDatabaseImpl(predefinedApiTypeLookupForHashing);
-    desugaredLibraryConfiguration = appView.options().desugaredLibraryConfiguration;
+    desugaredLibrarySpecification = appView.options().desugaredLibrarySpecification;
   }
 
   public static AndroidApiReferenceLevelCache create(
@@ -69,7 +69,7 @@
     if (reference.getContextType() == factory.objectType) {
       return appView.computedMinApiLevel();
     }
-    if (desugaredLibraryConfiguration.isSupported(reference, appView)) {
+    if (desugaredLibrarySpecification.isSupported(reference, appView)) {
       // If we end up desugaring the reference, the library classes is bridged by j$ which is part
       // of the program.
       return appView.computedMinApiLevel();
diff --git a/src/main/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryKeepRuleGenerator.java b/src/main/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryKeepRuleGenerator.java
index c7c920b..a720021 100644
--- a/src/main/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryKeepRuleGenerator.java
+++ b/src/main/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryKeepRuleGenerator.java
@@ -13,7 +13,7 @@
 import com.android.tools.r8.graph.DexProto;
 import com.android.tools.r8.graph.DexString;
 import com.android.tools.r8.graph.DexType;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
 import com.android.tools.r8.naming.NamingLens;
 import com.android.tools.r8.references.ArrayReference;
 import com.android.tools.r8.references.ClassReference;
@@ -71,7 +71,7 @@
       return false;
     }
     return namingLens.hasPrefixRewritingLogic()
-        || options.desugaredLibraryConfiguration.hasEmulatedLibraryInterfaces();
+        || options.desugaredLibrarySpecification.hasEmulatedLibraryInterfaces();
   }
 
   private void run() {
@@ -80,15 +80,15 @@
   }
 
   private Predicate<DexType> createTargetPredicate() {
-    DesugaredLibraryConfiguration desugaredLibraryConfiguration =
-        options.desugaredLibraryConfiguration;
+    LegacyDesugaredLibrarySpecification desugaredLibrarySpecification =
+        options.desugaredLibrarySpecification;
     Set<DexType> potentialTypesToKeep =
         SetUtils.newIdentityHashSet(
-            desugaredLibraryConfiguration.getCustomConversions().values(),
-            desugaredLibraryConfiguration.getEmulateLibraryInterface().values());
+            desugaredLibrarySpecification.getCustomConversions().values(),
+            desugaredLibrarySpecification.getEmulateLibraryInterface().values());
     byte[] synthesizedLibraryClassesPackageDescriptorPrefix =
         DexString.encodeToMutf8(
-            "L" + desugaredLibraryConfiguration.getSynthesizedLibraryClassesPackagePrefix());
+            "L" + desugaredLibrarySpecification.getSynthesizedLibraryClassesPackagePrefix());
     return type ->
         namingLens.prefixRewrittenType(type) != null
             || potentialTypesToKeep.contains(type)
diff --git a/src/main/java/com/android/tools/r8/dex/CodeToKeep.java b/src/main/java/com/android/tools/r8/dex/CodeToKeep.java
index 44affb4..cc05c31 100644
--- a/src/main/java/com/android/tools/r8/dex/CodeToKeep.java
+++ b/src/main/java/com/android/tools/r8/dex/CodeToKeep.java
@@ -25,7 +25,7 @@
 
   static CodeToKeep createCodeToKeep(InternalOptions options, NamingLens namingLens) {
     if ((!namingLens.hasPrefixRewritingLogic()
-            && !options.desugaredLibraryConfiguration.hasEmulatedLibraryInterfaces())
+            && !options.desugaredLibrarySpecification.hasEmulatedLibraryInterfaces())
         || options.isDesugaredLibraryCompilation()
         || options.testing.enableExperimentalDesugaredLibraryKeepRuleGenerator) {
       return new NopCodeToKeep();
@@ -65,9 +65,9 @@
       this.namingLens = namingLens;
       this.options = options;
       potentialTypesToKeep.addAll(
-          options.desugaredLibraryConfiguration.getEmulateLibraryInterface().values());
+          options.desugaredLibrarySpecification.getEmulateLibraryInterface().values());
       potentialTypesToKeep.addAll(
-          options.desugaredLibraryConfiguration.getCustomConversions().values());
+          options.desugaredLibrarySpecification.getCustomConversions().values());
     }
 
     private boolean shouldKeep(DexType type) {
@@ -77,7 +77,7 @@
           || type.toDescriptorString()
               .startsWith(
                   "L"
-                      + options.desugaredLibraryConfiguration
+                      + options.desugaredLibrarySpecification
                           .getSynthesizedLibraryClassesPackagePrefix());
     }
 
diff --git a/src/main/java/com/android/tools/r8/graph/AppView.java b/src/main/java/com/android/tools/r8/graph/AppView.java
index 7f4ccf5..c2316e4 100644
--- a/src/main/java/com/android/tools/r8/graph/AppView.java
+++ b/src/main/java/com/android/tools/r8/graph/AppView.java
@@ -160,7 +160,7 @@
 
   private static <T extends AppInfo> PrefixRewritingMapper defaultPrefixRewritingMapper(T appInfo) {
     InternalOptions options = appInfo.options();
-    return options.desugaredLibraryConfiguration.getPrefixRewritingMapper();
+    return options.desugaredLibrarySpecification.getPrefixRewritingMapper();
   }
 
   public static <T extends AppInfo> AppView<T> createForD8(T appInfo) {
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/BackportedMethodRewriter.java b/src/main/java/com/android/tools/r8/ir/desugar/BackportedMethodRewriter.java
index ed1260e..fba32bb 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/BackportedMethodRewriter.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/BackportedMethodRewriter.java
@@ -97,7 +97,7 @@
       AndroidApp androidApp, InternalOptions options, ExecutorService executor) throws IOException {
     List<DexMethod> methods = new ArrayList<>();
     PrefixRewritingMapper rewritePrefix =
-        options.desugaredLibraryConfiguration.getPrefixRewritingMapper();
+        options.desugaredLibrarySpecification.getPrefixRewritingMapper();
     AppInfo appInfo = null;
     if (androidApp != null) {
       DexApplication app =
@@ -135,13 +135,13 @@
         && appView.options().isDesugaredLibraryCompilation()
         && appView
             .options()
-            .desugaredLibraryConfiguration
+            .desugaredLibrarySpecification
             .getBackportCoreLibraryMember()
             .containsKey(method.holder)) {
       DexType newHolder =
           appView
               .options()
-              .desugaredLibraryConfiguration
+              .desugaredLibrarySpecification
               .getBackportCoreLibraryMember()
               .get(method.holder);
       DexMethod backportedMethod =
@@ -1366,7 +1366,7 @@
     }
 
     private void addProvider(MethodProvider generator) {
-      if (appView.options().desugaredLibraryConfiguration.isSupported(generator.method, appView)) {
+      if (appView.options().desugaredLibrarySpecification.isSupported(generator.method, appView)) {
         // TODO(b/174453232): Remove this after the configuration file format has bee updated
         // with the "rewrite_method" section.
         if (generator.method.getHolderType() == appView.dexItemFactory().objectsType) {
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/CfPostProcessingDesugaringCollection.java b/src/main/java/com/android/tools/r8/ir/desugar/CfPostProcessingDesugaringCollection.java
index 064e82d..09272ea 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/CfPostProcessingDesugaringCollection.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/CfPostProcessingDesugaringCollection.java
@@ -57,7 +57,7 @@
         InterfaceMethodProcessorFacade interfaceMethodProcessorFacade,
         RetargetingInfo retargetingInfo) {
       ArrayList<CfPostProcessingDesugaring> desugarings = new ArrayList<>();
-      if (!appView.options().desugaredLibraryConfiguration.getRetargetCoreLibMember().isEmpty()
+      if (!appView.options().desugaredLibrarySpecification.getRetargetCoreLibMember().isEmpty()
           && !appView.options().isDesugaredLibraryCompilation()) {
         desugarings.add(new DesugaredLibraryRetargeterPostProcessor(appView, retargetingInfo));
       }
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/NonEmptyCfInstructionDesugaringCollection.java b/src/main/java/com/android/tools/r8/ir/desugar/NonEmptyCfInstructionDesugaringCollection.java
index f722159..04b755f 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/NonEmptyCfInstructionDesugaringCollection.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/NonEmptyCfInstructionDesugaringCollection.java
@@ -79,7 +79,7 @@
     this.nestBasedAccessDesugaring = NestBasedAccessDesugaring.create(appView);
     BackportedMethodRewriter backportedMethodRewriter = null;
     desugaredLibraryRetargeter =
-        appView.options().desugaredLibraryConfiguration.getRetargetCoreLibMember().isEmpty()
+        appView.options().desugaredLibrarySpecification.getRetargetCoreLibMember().isEmpty()
             ? null
             : new DesugaredLibraryRetargeter(appView);
     if (desugaredLibraryRetargeter != null) {
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryAPICallbackSynthesizer.java b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryAPICallbackSynthesizer.java
index 92d7b92..e95ae91 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryAPICallbackSynthesizer.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryAPICallbackSynthesizer.java
@@ -109,7 +109,7 @@
     if (!appView.rewritePrefix.hasRewrittenTypeInSignature(definition.getProto(), appView)
         || appView
             .options()
-            .desugaredLibraryConfiguration
+            .desugaredLibrarySpecification
             .getEmulateLibraryInterface()
             .containsKey(method.getHolderType())) {
       return false;
@@ -127,7 +127,7 @@
         return false;
       }
     }
-    if (!appView.options().desugaredLibraryConfiguration.supportAllCallbacksFromLibrary
+    if (!appView.options().desugaredLibrarySpecification.supportAllCallbacksFromLibrary
         && appView.options().isDesugaredLibraryCompilation()) {
       return false;
     }
@@ -178,11 +178,11 @@
   }
 
   private boolean shouldGenerateCallbacksForEmulateInterfaceAPIs(DexClass dexClass) {
-    if (appView.options().desugaredLibraryConfiguration.supportAllCallbacksFromLibrary) {
+    if (appView.options().desugaredLibrarySpecification.supportAllCallbacksFromLibrary) {
       return true;
     }
     Map<DexType, DexType> emulateLibraryInterfaces =
-        appView.options().desugaredLibraryConfiguration.getEmulateLibraryInterface();
+        appView.options().desugaredLibrarySpecification.getEmulateLibraryInterface();
     return !(emulateLibraryInterfaces.containsKey(dexClass.type)
         || emulateLibraryInterfaces.containsValue(dexClass.type));
   }
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryAPIConverter.java b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryAPIConverter.java
index 460c350..8e20905 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryAPIConverter.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryAPIConverter.java
@@ -181,7 +181,7 @@
     return interfaceResult != null
         && appView
             .options()
-            .desugaredLibraryConfiguration
+            .desugaredLibrarySpecification
             .getEmulateLibraryInterface()
             .containsKey(interfaceResult.getHolderType());
   }
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryRetargeter.java b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryRetargeter.java
index 01c504c..c570091 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryRetargeter.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryRetargeter.java
@@ -130,7 +130,7 @@
     }
     if (appView
         .options()
-        .desugaredLibraryConfiguration
+        .desugaredLibrarySpecification
         .getDontRetargetLibMember()
         .contains(context.getContextType())) {
       return NO_REWRITING;
@@ -149,7 +149,7 @@
       // Final methods can be rewritten as a normal invoke.
       if (superTarget != null && !superTarget.getAccessFlags().isFinal()) {
         return InvokeRetargetingResult.createInvokeRetargetingResult(
-            appView.options().desugaredLibraryConfiguration.retargetMethod(superTarget, appView));
+            appView.options().desugaredLibrarySpecification.retargetMethod(superTarget, appView));
       }
     }
     return retarget;
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryRetargeterL8Synthesizer.java b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryRetargeterL8Synthesizer.java
index 73cbd3d..2ccd9d2 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryRetargeterL8Synthesizer.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryRetargeterL8Synthesizer.java
@@ -19,7 +19,7 @@
       AppView<?> appView, RetargetingInfo retargetingInfo) {
     assert appView.options().isDesugaredLibraryCompilation();
     if (retargetingInfo == null || retargetingInfo.getEmulatedDispatchMethods().isEmpty()) {
-      assert appView.options().desugaredLibraryConfiguration.getRetargetCoreLibMember().isEmpty();
+      assert appView.options().desugaredLibrarySpecification.getRetargetCoreLibMember().isEmpty();
       return null;
     }
     return new DesugaredLibraryRetargeterL8Synthesizer(appView, retargetingInfo);
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryRetargeterLibraryTypeSynthesizer.java b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryRetargeterLibraryTypeSynthesizer.java
index faa5857..b9c6593 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryRetargeterLibraryTypeSynthesizer.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryRetargeterLibraryTypeSynthesizer.java
@@ -40,7 +40,7 @@
 
   public static void checkForAssumedLibraryTypes(AppView<?> appView) {
     Map<DexString, Map<DexType, DexType>> retargetCoreLibMember =
-        appView.options().desugaredLibraryConfiguration.getRetargetCoreLibMember();
+        appView.options().desugaredLibrarySpecification.getRetargetCoreLibMember();
     for (DexString methodName : retargetCoreLibMember.keySet()) {
       for (DexType inType : retargetCoreLibMember.get(methodName).keySet()) {
         DexClass typeClass = appView.definitionFor(inType);
@@ -53,7 +53,7 @@
 
   public static void amendLibraryWithRetargetedMembers(AppView<AppInfoWithClassHierarchy> appView) {
     Map<DexString, Map<DexType, DexType>> retargetCoreLibMember =
-        appView.options().desugaredLibraryConfiguration.getRetargetCoreLibMember();
+        appView.options().desugaredLibrarySpecification.getRetargetCoreLibMember();
     Map<DexType, DexLibraryClass> synthesizedLibraryClasses =
         synthesizeLibraryClassesForRetargetedMembers(appView, retargetCoreLibMember);
     Map<DexLibraryClass, Set<DexEncodedMethod>> synthesizedLibraryMethods =
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryRetargeterPostProcessor.java b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryRetargeterPostProcessor.java
index 1a2adfb..74aa92a 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryRetargeterPostProcessor.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryRetargeterPostProcessor.java
@@ -123,7 +123,7 @@
       }
       if (appView
           .options()
-          .desugaredLibraryConfiguration
+          .desugaredLibrarySpecification
           .getDontRetargetLibMember()
           .contains(clazz.getType())) {
         continue;
@@ -144,7 +144,7 @@
     // even if this results in invalid code, these classes are never desugared.
     // In desugared library, emulated interface methods can be overridden by retarget lib members.
     DexMethod forwardMethod =
-        appView.options().desugaredLibraryConfiguration.retargetMethod(target, appView);
+        appView.options().desugaredLibrarySpecification.retargetMethod(target, appView);
     assert forwardMethod != null && forwardMethod != target.getReference();
     DexEncodedMethod desugaringForwardingMethod =
         DexEncodedMethod.createDesugaringForwardingMethod(
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryRetargeterSyntheticHelper.java b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryRetargeterSyntheticHelper.java
index 5dde56e..34bbcc2 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryRetargeterSyntheticHelper.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryRetargeterSyntheticHelper.java
@@ -151,7 +151,7 @@
           DexMethod desugarMethod =
               appView
                   .options()
-                  .desugaredLibraryConfiguration
+                  .desugaredLibrarySpecification
                   .retargetMethod(emulatedDispatchMethod, appView);
           assert desugarMethod
               != null; // This method is reached only for retarget core lib members.
@@ -178,7 +178,7 @@
 
   private void rewriteType(DexType type) {
     String newName =
-        appView.options().desugaredLibraryConfiguration.convertJavaNameToDesugaredLibrary(type);
+        appView.options().desugaredLibrarySpecification.convertJavaNameToDesugaredLibrary(type);
     DexType newType =
         appView.dexItemFactory().createType(DescriptorUtils.javaTypeToDescriptor(newName));
     appView.rewritePrefix.rewriteType(type, newType);
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryWrapperSynthesizer.java b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryWrapperSynthesizer.java
index 14240a6..a885766 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryWrapperSynthesizer.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryWrapperSynthesizer.java
@@ -27,6 +27,7 @@
 import com.android.tools.r8.ir.desugar.CfClassSynthesizerDesugaringEventConsumer;
 import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryWrapperSynthesizerEventConsumer.DesugaredLibraryClasspathWrapperSynthesizeEventConsumer;
 import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryWrapperSynthesizerEventConsumer.DesugaredLibraryL8ProgramWrapperSynthesizerEventConsumer;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
 import com.android.tools.r8.ir.synthetic.DesugaredLibraryAPIConversionCfCodeProvider.APIConverterConstructorCfCodeProvider;
 import com.android.tools.r8.ir.synthetic.DesugaredLibraryAPIConversionCfCodeProvider.APIConverterThrowRuntimeExceptionCfCodeProvider;
 import com.android.tools.r8.ir.synthetic.DesugaredLibraryAPIConversionCfCodeProvider.APIConverterVivifiedWrapperCfCodeProvider;
@@ -178,7 +179,7 @@
     // ConversionType holds the methods "rewrittenType convert(type)" and the other way around.
     // But everything is going to be rewritten, so we need to use vivifiedType and type".
     DexType conversionHolder =
-        appView.options().desugaredLibraryConfiguration.getCustomConversions().get(type);
+        appView.options().desugaredLibrarySpecification.getCustomConversions().get(type);
     if (conversionHolder != null) {
       return factory.createMethod(
           conversionHolder, factory.createProto(destType, srcType), factory.convertMethodName);
@@ -187,7 +188,7 @@
   }
 
   private boolean canConvert(DexType type) {
-    return appView.options().desugaredLibraryConfiguration.getCustomConversions().containsKey(type)
+    return appView.options().desugaredLibrarySpecification.getCustomConversions().containsKey(type)
         || canGenerateWrapper(type);
   }
 
@@ -215,7 +216,7 @@
   }
 
   private boolean canGenerateWrapper(DexType type) {
-    return appView.options().desugaredLibraryConfiguration.getWrapperConversions().contains(type);
+    return appView.options().desugaredLibrarySpecification.getWrapperConversions().contains(type);
   }
 
   private DexClass getValidClassToWrap(DexType type) {
@@ -476,7 +477,7 @@
       if (holderClass == null) {
         assert appView
             .options()
-            .desugaredLibraryConfiguration
+            .desugaredLibrarySpecification
             .getEmulateLibraryInterface()
             .containsValue(dexEncodedMethod.getHolderType());
         isInterface = true;
@@ -666,10 +667,10 @@
   // conversion methods are present.
   @Override
   public void synthesizeClasses(CfClassSynthesizerDesugaringEventConsumer eventConsumer) {
-    DesugaredLibraryConfiguration conf = appView.options().desugaredLibraryConfiguration;
+    LegacyDesugaredLibrarySpecification spec = appView.options().desugaredLibrarySpecification;
     List<DexProgramClass> validClassesToWrap = new ArrayList<>();
-    for (DexType type : conf.getWrapperConversions()) {
-      assert !conf.getCustomConversions().containsKey(type);
+    for (DexType type : spec.getWrapperConversions()) {
+      assert !spec.getCustomConversions().containsKey(type);
       DexClass validClassToWrap = getValidClassToWrap(type);
       // In broken set-ups we can end up having a json files containing wrappers of non desugared
       // classes. Such wrappers are not required since the class won't be rewritten.
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/RetargetingInfo.java b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/RetargetingInfo.java
index 525801f..5e5fc52 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/RetargetingInfo.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/RetargetingInfo.java
@@ -11,6 +11,7 @@
 import com.android.tools.r8.graph.DexProto;
 import com.android.tools.r8.graph.DexString;
 import com.android.tools.r8.graph.DexType;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
 import com.android.tools.r8.utils.WorkList;
 import com.android.tools.r8.utils.collections.DexClassAndMethodSet;
 import com.google.common.collect.ImmutableMap;
@@ -66,10 +67,10 @@
     }
 
     private RetargetingInfo computeRetargetingInfo() {
-      DesugaredLibraryConfiguration desugaredLibraryConfiguration =
-          appView.options().desugaredLibraryConfiguration;
+      LegacyDesugaredLibrarySpecification desugaredLibrarySpecification =
+          appView.options().desugaredLibrarySpecification;
       Map<DexString, Map<DexType, DexType>> retargetCoreLibMember =
-          desugaredLibraryConfiguration.getRetargetCoreLibMember();
+          desugaredLibrarySpecification.getRetargetCoreLibMember();
       if (retargetCoreLibMember.isEmpty()) {
         return new RetargetingInfo(
             ImmutableMap.of(), ImmutableMap.of(), DexClassAndMethodSet.empty());
@@ -108,7 +109,7 @@
           }
         }
       }
-      if (desugaredLibraryConfiguration.isLibraryCompilation()) {
+      if (desugaredLibrarySpecification.isLibraryCompilation()) {
         // TODO(b/177977763): This is only a workaround rewriting invokes of j.u.Arrays.deepEquals0
         // to j.u.DesugarArrays.deepEquals0.
         DexItemFactory itemFactory = appView.options().dexItemFactory();
@@ -152,7 +153,7 @@
     private boolean isEmulatedInterfaceDispatch(DexClassAndMethod method) {
       // Answers true if this method is already managed through emulated interface dispatch.
       Map<DexType, DexType> emulateLibraryInterface =
-          appView.options().desugaredLibraryConfiguration.getEmulateLibraryInterface();
+          appView.options().desugaredLibrarySpecification.getEmulateLibraryInterface();
       if (emulateLibraryInterface.isEmpty()) {
         return false;
       }
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryConfiguration.java b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/legacyspecification/LegacyDesugaredLibrarySpecification.java
similarity index 94%
rename from src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryConfiguration.java
rename to src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/legacyspecification/LegacyDesugaredLibrarySpecification.java
index 326b3c9..87ac465 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryConfiguration.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/legacyspecification/LegacyDesugaredLibrarySpecification.java
@@ -1,7 +1,7 @@
 // Copyright (c) 2021, the R8 project authors. Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
-package com.android.tools.r8.ir.desugar.desugaredlibrary;
+package com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification;
 
 import com.android.tools.r8.errors.CompilationError;
 import com.android.tools.r8.graph.AppView;
@@ -35,7 +35,7 @@
 import java.util.Set;
 import java.util.stream.Collectors;
 
-public class DesugaredLibraryConfiguration {
+public class LegacyDesugaredLibrarySpecification {
   public static final String FALL_BACK_SYNTHESIZED_CLASSES_PACKAGE_PREFIX = "j$/";
   public static final boolean FALL_BACK_SUPPORT_ALL_CALLBACKS_FROM_LIBRARY = true;
   private final AndroidApiLevel requiredCompilationAPILevel;
@@ -66,9 +66,9 @@
     return new Builder(dexItemFactory, reporter, origin);
   }
 
-  public static DesugaredLibraryConfiguration withOnlyRewritePrefixForTesting(
+  public static LegacyDesugaredLibrarySpecification withOnlyRewritePrefixForTesting(
       Map<String, String> prefix, InternalOptions options) {
-    return new DesugaredLibraryConfiguration(
+    return new LegacyDesugaredLibrarySpecification(
         AndroidApiLevel.B,
         true,
         FALL_BACK_SYNTHESIZED_CLASSES_PACKAGE_PREFIX,
@@ -87,8 +87,8 @@
         new DesugarPrefixRewritingMapper(prefix, options.itemFactory, true));
   }
 
-  public static DesugaredLibraryConfiguration empty() {
-    return new DesugaredLibraryConfiguration(
+  public static LegacyDesugaredLibrarySpecification empty() {
+    return new LegacyDesugaredLibrarySpecification(
         AndroidApiLevel.B,
         false,
         FALL_BACK_SYNTHESIZED_CLASSES_PACKAGE_PREFIX,
@@ -118,7 +118,7 @@
     };
   }
 
-  private DesugaredLibraryConfiguration(
+  private LegacyDesugaredLibrarySpecification(
       AndroidApiLevel requiredCompilationAPILevel,
       boolean libraryCompilation,
       String packagePrefix,
@@ -337,7 +337,7 @@
           rewritePrefix,
           prefix,
           rewrittenPrefix,
-          DesugaredLibraryConfigurationParser.REWRITE_PREFIX_KEY);
+          LegacyDesugaredLibrarySpecificationParser.REWRITE_PREFIX_KEY);
       return this;
     }
 
@@ -349,7 +349,7 @@
           emulateLibraryInterface,
           interfaceType,
           rewrittenType,
-          DesugaredLibraryConfigurationParser.EMULATE_INTERFACE_KEY);
+          LegacyDesugaredLibrarySpecificationParser.EMULATE_INTERFACE_KEY);
       return this;
     }
 
@@ -360,7 +360,7 @@
           customConversions,
           dexType,
           conversionType,
-          DesugaredLibraryConfigurationParser.CUSTOM_CONVERSION_KEY);
+          LegacyDesugaredLibrarySpecificationParser.CUSTOM_CONVERSION_KEY);
       return this;
     }
 
@@ -382,7 +382,7 @@
           typeMap,
           originalType,
           finalType,
-          DesugaredLibraryConfigurationParser.RETARGET_LIB_MEMBER_KEY);
+          LegacyDesugaredLibrarySpecificationParser.RETARGET_LIB_MEMBER_KEY);
       return this;
     }
 
@@ -393,7 +393,7 @@
           backportCoreLibraryMember,
           backportType,
           rewrittenBackportType,
-          DesugaredLibraryConfigurationParser.BACKPORT_KEY);
+          LegacyDesugaredLibrarySpecificationParser.BACKPORT_KEY);
       return this;
     }
 
@@ -428,9 +428,9 @@
       this.supportAllCallbacksFromLibrary = supportAllCallbacksFromLibrary;
     }
 
-    public DesugaredLibraryConfiguration build() {
+    public LegacyDesugaredLibrarySpecification build() {
       validate();
-      return new DesugaredLibraryConfiguration(
+      return new LegacyDesugaredLibrarySpecification(
           requiredCompilationAPILevel,
           libraryCompilation,
           synthesizedLibraryClassesPackagePrefix,
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryConfigurationParser.java b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/legacyspecification/LegacyDesugaredLibrarySpecificationParser.java
similarity index 82%
rename from src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryConfigurationParser.java
rename to src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/legacyspecification/LegacyDesugaredLibrarySpecificationParser.java
index f8b69f6..ba53f55 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/DesugaredLibraryConfigurationParser.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/desugaredlibrary/legacyspecification/LegacyDesugaredLibrarySpecificationParser.java
@@ -2,7 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-package com.android.tools.r8.ir.desugar.desugaredlibrary;
+package com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification;
 
 import com.android.tools.r8.StringResource;
 import com.android.tools.r8.graph.DexItemFactory;
@@ -21,7 +21,7 @@
 import java.util.Map;
 import java.util.function.Consumer;
 
-public class DesugaredLibraryConfigurationParser {
+public class LegacyDesugaredLibrarySpecificationParser {
 
   public static final int MAX_SUPPORTED_VERSION = 4;
   public static final SemanticVersion MIN_SUPPORTED_VERSION = new SemanticVersion(1, 0, 9);
@@ -55,10 +55,10 @@
   private final boolean libraryCompilation;
   private final int minAPILevel;
 
-  private DesugaredLibraryConfiguration.Builder configurationBuilder = null;
+  private LegacyDesugaredLibrarySpecification.Builder specificationBuilder = null;
   private Origin origin;
 
-  public DesugaredLibraryConfigurationParser(
+  public LegacyDesugaredLibrarySpecificationParser(
       DexItemFactory dexItemFactory,
       Reporter reporter,
       boolean libraryCompilation,
@@ -79,20 +79,21 @@
     return json.get(key);
   }
 
-  public DesugaredLibraryConfiguration parse(StringResource stringResource) {
+  public LegacyDesugaredLibrarySpecification parse(StringResource stringResource) {
     return parse(stringResource, builder -> {});
   }
 
-  public DesugaredLibraryConfiguration parse(
+  public LegacyDesugaredLibrarySpecification parse(
       StringResource stringResource,
-      Consumer<DesugaredLibraryConfiguration.Builder> configurationAmender) {
+      Consumer<LegacyDesugaredLibrarySpecification.Builder> configurationAmender) {
     origin = stringResource.getOrigin();
     assert origin != null;
-    configurationBuilder = DesugaredLibraryConfiguration.builder(dexItemFactory, reporter, origin);
+    specificationBuilder =
+        LegacyDesugaredLibrarySpecification.builder(dexItemFactory, reporter, origin);
     if (libraryCompilation) {
-      configurationBuilder.setLibraryCompilation();
+      specificationBuilder.setLibraryCompilation();
     } else {
-      configurationBuilder.setProgramCompilation();
+      specificationBuilder.setProgramCompilation();
     }
     String jsonConfigString;
     JsonObject jsonConfig;
@@ -104,7 +105,7 @@
       throw reporter.fatalError(new ExceptionDiagnostic(e, origin));
     }
 
-    configurationBuilder.setJsonSource(jsonConfigString);
+    specificationBuilder.setJsonSource(jsonConfigString);
 
     JsonElement formatVersionElement = required(jsonConfig, CONFIGURATION_FORMAT_VERSION_KEY);
     int formatVersion = formatVersionElement.getAsInt();
@@ -132,13 +133,13 @@
     String groupID = required(jsonConfig, GROUP_ID_KEY).getAsString();
     String artifactID = required(jsonConfig, ARTIFACT_ID_KEY).getAsString();
     String identifier = String.join(":", groupID, artifactID, version);
-    configurationBuilder.setDesugaredLibraryIdentifier(identifier);
-    configurationBuilder.setSynthesizedLibraryClassesPackagePrefix(
+    specificationBuilder.setDesugaredLibraryIdentifier(identifier);
+    specificationBuilder.setSynthesizedLibraryClassesPackagePrefix(
         required(jsonConfig, SYNTHESIZED_LIBRARY_CLASSES_PACKAGE_PREFIX_KEY).getAsString());
 
     int required_compilation_api_level =
         required(jsonConfig, REQUIRED_COMPILATION_API_LEVEL_KEY).getAsInt();
-    configurationBuilder.setRequiredCompilationAPILevel(
+    specificationBuilder.setRequiredCompilationAPILevel(
         AndroidApiLevel.getAndroidApiLevel(required_compilation_api_level));
     JsonElement commonFlags = required(jsonConfig, COMMON_FLAGS_KEY);
     JsonElement libraryFlags = required(jsonConfig, LIBRARY_FLAGS_KEY);
@@ -152,17 +153,17 @@
       for (JsonElement keepRule : jsonKeepRules) {
         extraKeepRules.add(keepRule.getAsString());
       }
-      configurationBuilder.setExtraKeepRules(extraKeepRules);
+      specificationBuilder.setExtraKeepRules(extraKeepRules);
     }
 
     if (jsonConfig.has(SUPPORT_ALL_CALLBACKS_FROM_LIBRARY_KEY)) {
       boolean supportAllCallbacksFromLibrary =
           jsonConfig.get(SUPPORT_ALL_CALLBACKS_FROM_LIBRARY_KEY).getAsBoolean();
-      configurationBuilder.setSupportAllCallbacksFromLibrary(supportAllCallbacksFromLibrary);
+      specificationBuilder.setSupportAllCallbacksFromLibrary(supportAllCallbacksFromLibrary);
     }
-    configurationAmender.accept(configurationBuilder);
-    DesugaredLibraryConfiguration config = configurationBuilder.build();
-    configurationBuilder = null;
+    configurationAmender.accept(specificationBuilder);
+    LegacyDesugaredLibrarySpecification config = specificationBuilder.build();
+    specificationBuilder = null;
     origin = null;
     return config;
   }
@@ -181,52 +182,52 @@
     if (jsonFlagSet.has(REWRITE_PREFIX_KEY)) {
       for (Map.Entry<String, JsonElement> rewritePrefix :
           jsonFlagSet.get(REWRITE_PREFIX_KEY).getAsJsonObject().entrySet()) {
-        configurationBuilder.putRewritePrefix(
+        specificationBuilder.putRewritePrefix(
             rewritePrefix.getKey(), rewritePrefix.getValue().getAsString());
       }
     }
     if (jsonFlagSet.has(RETARGET_LIB_MEMBER_KEY)) {
       for (Map.Entry<String, JsonElement> retarget :
           jsonFlagSet.get(RETARGET_LIB_MEMBER_KEY).getAsJsonObject().entrySet()) {
-        configurationBuilder.putRetargetCoreLibMember(
+        specificationBuilder.putRetargetCoreLibMember(
             retarget.getKey(), retarget.getValue().getAsString());
       }
     }
     if (jsonFlagSet.has(BACKPORT_KEY)) {
       for (Map.Entry<String, JsonElement> backport :
           jsonFlagSet.get(BACKPORT_KEY).getAsJsonObject().entrySet()) {
-        configurationBuilder.putBackportCoreLibraryMember(
+        specificationBuilder.putBackportCoreLibraryMember(
             backport.getKey(), backport.getValue().getAsString());
       }
     }
     if (jsonFlagSet.has(EMULATE_INTERFACE_KEY)) {
       for (Map.Entry<String, JsonElement> itf :
           jsonFlagSet.get(EMULATE_INTERFACE_KEY).getAsJsonObject().entrySet()) {
-        configurationBuilder.putEmulateLibraryInterface(itf.getKey(), itf.getValue().getAsString());
+        specificationBuilder.putEmulateLibraryInterface(itf.getKey(), itf.getValue().getAsString());
       }
     }
     if (jsonFlagSet.has(CUSTOM_CONVERSION_KEY)) {
       for (Map.Entry<String, JsonElement> conversion :
           jsonFlagSet.get(CUSTOM_CONVERSION_KEY).getAsJsonObject().entrySet()) {
-        configurationBuilder.putCustomConversion(
+        specificationBuilder.putCustomConversion(
             conversion.getKey(), conversion.getValue().getAsString());
       }
     }
     if (jsonFlagSet.has(WRAPPER_CONVERSION_KEY)) {
       for (JsonElement wrapper : jsonFlagSet.get(WRAPPER_CONVERSION_KEY).getAsJsonArray()) {
-        configurationBuilder.addWrapperConversion(wrapper.getAsString());
+        specificationBuilder.addWrapperConversion(wrapper.getAsString());
       }
     }
     if (jsonFlagSet.has(DONT_REWRITE_KEY)) {
       JsonArray dontRewrite = jsonFlagSet.get(DONT_REWRITE_KEY).getAsJsonArray();
       for (JsonElement rewrite : dontRewrite) {
-        configurationBuilder.addDontRewriteInvocation(rewrite.getAsString());
+        specificationBuilder.addDontRewriteInvocation(rewrite.getAsString());
       }
     }
     if (jsonFlagSet.has(DONT_RETARGET_LIB_MEMBER_KEY)) {
       JsonArray dontRetarget = jsonFlagSet.get(DONT_RETARGET_LIB_MEMBER_KEY).getAsJsonArray();
       for (JsonElement rewrite : dontRetarget) {
-        configurationBuilder.addDontRetargetLibMember(rewrite.getAsString());
+        specificationBuilder.addDontRetargetLibMember(rewrite.getAsString());
       }
     }
   }
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/itf/ClassProcessor.java b/src/main/java/com/android/tools/r8/ir/desugar/itf/ClassProcessor.java
index 36519f8..0d79ac1 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/itf/ClassProcessor.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/itf/ClassProcessor.java
@@ -376,10 +376,10 @@
     this.dexItemFactory = appView.dexItemFactory();
     this.helper = new InterfaceDesugaringSyntheticHelper(appView);
     needsLibraryInfo =
-        !appView.options().desugaredLibraryConfiguration.getEmulateLibraryInterface().isEmpty()
+        !appView.options().desugaredLibrarySpecification.getEmulateLibraryInterface().isEmpty()
             || !appView
                 .options()
-                .desugaredLibraryConfiguration
+                .desugaredLibrarySpecification
                 .getRetargetCoreLibMember()
                 .isEmpty();
     this.isLiveMethod = isLiveMethod;
@@ -510,7 +510,7 @@
       DexClass iface = appView.definitionFor(emulatedInterface);
       if (iface != null) {
         assert iface.isLibraryClass()
-            || appView.options().desugaredLibraryConfiguration.isLibraryCompilation();
+            || appView.options().desugaredLibrarySpecification.isLibraryCompilation();
         workList.addIfNotSeen(iface.getInterfaces());
       }
     }
@@ -761,7 +761,7 @@
     assert needsLibraryInfo();
     assert method.getDefinition().isNonPrivateVirtualMethod();
     return !method.getAccessFlags().isFinal()
-        && appView.options().desugaredLibraryConfiguration.retargetMethod(method, appView) != null;
+        && appView.options().desugaredLibrarySpecification.retargetMethod(method, appView) != null;
   }
 
   private boolean dontRewrite(DexClassAndMethod method) {
@@ -850,7 +850,7 @@
     DexMethod forwardMethod =
         target.getHolder().isInterface()
             ? helper.ensureDefaultAsMethodOfCompanionClassStub(target).getReference()
-            : appView.options().desugaredLibraryConfiguration.retargetMethod(target, appView);
+            : appView.options().desugaredLibrarySpecification.retargetMethod(target, appView);
     DexEncodedMethod desugaringForwardingMethod =
         DexEncodedMethod.createDesugaringForwardingMethod(
             target, clazz, forwardMethod, dexItemFactory);
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/itf/EmulatedInterfaceApplicationRewriter.java b/src/main/java/com/android/tools/r8/ir/desugar/itf/EmulatedInterfaceApplicationRewriter.java
index af7fb9f..74d94e3 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/itf/EmulatedInterfaceApplicationRewriter.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/itf/EmulatedInterfaceApplicationRewriter.java
@@ -26,7 +26,7 @@
   public EmulatedInterfaceApplicationRewriter(AppView<?> appView) {
     this.appView = appView;
     this.emulatedInterfaces =
-        appView.options().desugaredLibraryConfiguration.getEmulateLibraryInterface();
+        appView.options().desugaredLibrarySpecification.getEmulateLibraryInterface();
   }
 
   public void rewriteApplication(DexApplication.Builder<?> builder) {
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/itf/InterfaceDesugaringSyntheticHelper.java b/src/main/java/com/android/tools/r8/ir/desugar/itf/InterfaceDesugaringSyntheticHelper.java
index 0dc7375..a4800c3 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/itf/InterfaceDesugaringSyntheticHelper.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/itf/InterfaceDesugaringSyntheticHelper.java
@@ -69,7 +69,7 @@
   public InterfaceDesugaringSyntheticHelper(AppView<?> appView) {
     this.appView = appView;
     emulatedInterfaces =
-        appView.options().desugaredLibraryConfiguration.getEmulateLibraryInterface();
+        appView.options().desugaredLibrarySpecification.getEmulateLibraryInterface();
 
     this.shouldIgnoreFromReportsPredicate = getShouldIgnoreFromReportsPredicate(appView);
   }
@@ -100,7 +100,7 @@
 
   boolean dontRewrite(DexClassAndMethod method) {
     for (Pair<DexType, DexString> dontRewrite :
-        appView.options().desugaredLibraryConfiguration.getDontRewriteInvocation()) {
+        appView.options().desugaredLibrarySpecification.getDontRewriteInvocation()) {
       if (method.getHolderType() == dontRewrite.getFirst()
           && method.getName() == dontRewrite.getSecond()) {
         return true;
@@ -515,7 +515,7 @@
       return appView.rewritePrefix.hasRewrittenType(type, appView)
           || descriptor.endsWith(companionClassNameDescriptorSuffix)
           || isRewrittenEmulatedInterface(type)
-          || options.desugaredLibraryConfiguration.getCustomConversions().containsValue(type)
+          || options.desugaredLibrarySpecification.getCustomConversions().containsValue(type)
           || appView.getDontWarnConfiguration().matches(type);
     };
   }
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/itf/InterfaceMethodRewriter.java b/src/main/java/com/android/tools/r8/ir/desugar/itf/InterfaceMethodRewriter.java
index 2152ef0..a40d69a 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/itf/InterfaceMethodRewriter.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/itf/InterfaceMethodRewriter.java
@@ -35,7 +35,7 @@
 import com.android.tools.r8.ir.desugar.DesugarDescription;
 import com.android.tools.r8.ir.desugar.FreshLocalProvider;
 import com.android.tools.r8.ir.desugar.LocalStackAllocator;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
 import com.android.tools.r8.ir.desugar.icce.AlwaysThrowingInstructionDesugaring;
 import com.android.tools.r8.ir.desugar.lambda.LambdaInstructionDesugaring;
 import com.android.tools.r8.ir.desugar.stringconcat.StringConcatInstructionDesugaring;
@@ -120,11 +120,11 @@
   }
 
   public static void checkForAssumedLibraryTypes(AppInfo appInfo, InternalOptions options) {
-    DesugaredLibraryConfiguration config = options.desugaredLibraryConfiguration;
+    LegacyDesugaredLibrarySpecification spec = options.desugaredLibrarySpecification;
     BiConsumer<DexType, DexType> registerEntry = registerMapEntry(appInfo);
-    config.getEmulateLibraryInterface().forEach(registerEntry);
-    config.getCustomConversions().forEach(registerEntry);
-    config.getRetargetCoreLibMember().forEach((method, types) -> types.forEach(registerEntry));
+    spec.getEmulateLibraryInterface().forEach(registerEntry);
+    spec.getCustomConversions().forEach(registerEntry);
+    spec.getRetargetCoreLibMember().forEach((method, types) -> types.forEach(registerEntry));
   }
 
   private static BiConsumer<DexType, DexType> registerMapEntry(AppInfo appInfo) {
@@ -158,7 +158,7 @@
 
   private void initializeEmulatedInterfaceVariables() {
     Map<DexType, DexType> emulateLibraryInterface =
-        options.desugaredLibraryConfiguration.getEmulateLibraryInterface();
+        options.desugaredLibrarySpecification.getEmulateLibraryInterface();
     for (DexType interfaceType : emulateLibraryInterface.keySet()) {
       addRewriteRulesForEmulatedInterface(
           interfaceType, emulateLibraryInterface.get(interfaceType).toSourceString());
@@ -776,7 +776,7 @@
       // method (method is on desugared library). Find out if it needs to be
       // retargeted or if it just calls a companion class method and rewrite.
       DexMethod retargetMethod =
-          options.desugaredLibraryConfiguration.retargetMethod(superTarget, appView);
+          options.desugaredLibrarySpecification.retargetMethod(superTarget, appView);
       if (retargetMethod != null) {
         return DesugarDescription.builder()
             .setDesugarRewrite(
diff --git a/src/main/java/com/android/tools/r8/ir/desugar/itf/ProgramEmulatedInterfaceSynthesizer.java b/src/main/java/com/android/tools/r8/ir/desugar/itf/ProgramEmulatedInterfaceSynthesizer.java
index d68dec8..5c2ec42 100644
--- a/src/main/java/com/android/tools/r8/ir/desugar/itf/ProgramEmulatedInterfaceSynthesizer.java
+++ b/src/main/java/com/android/tools/r8/ir/desugar/itf/ProgramEmulatedInterfaceSynthesizer.java
@@ -41,7 +41,7 @@
 
   public static ProgramEmulatedInterfaceSynthesizer create(AppView<?> appView) {
     if (!appView.options().isDesugaredLibraryCompilation()
-        || appView.options().desugaredLibraryConfiguration.getEmulateLibraryInterface().isEmpty()) {
+        || appView.options().desugaredLibrarySpecification.getEmulateLibraryInterface().isEmpty()) {
       return null;
     }
     return new ProgramEmulatedInterfaceSynthesizer(appView);
@@ -166,7 +166,7 @@
     // In practice, there is usually a single case (except for tests),
     // so we do not bother to make the following loop more clever.
     Map<DexString, Map<DexType, DexType>> retargetCoreLibMember =
-        appView.options().desugaredLibraryConfiguration.getRetargetCoreLibMember();
+        appView.options().desugaredLibrarySpecification.getRetargetCoreLibMember();
     for (DexString methodName : retargetCoreLibMember.keySet()) {
       if (method.getName() == methodName) {
         for (DexType inType : retargetCoreLibMember.get(methodName).keySet()) {
diff --git a/src/main/java/com/android/tools/r8/shaking/L8TreePruner.java b/src/main/java/com/android/tools/r8/shaking/L8TreePruner.java
index c42b3e0..960ccd5 100644
--- a/src/main/java/com/android/tools/r8/shaking/L8TreePruner.java
+++ b/src/main/java/com/android/tools/r8/shaking/L8TreePruner.java
@@ -28,9 +28,9 @@
 
   public L8TreePruner(InternalOptions options) {
     this.options = options;
-    backports.addAll(options.desugaredLibraryConfiguration.getBackportCoreLibraryMember().keySet());
+    backports.addAll(options.desugaredLibrarySpecification.getBackportCoreLibraryMember().keySet());
     emulatedInterfaces.addAll(
-        options.desugaredLibraryConfiguration.getEmulateLibraryInterface().keySet());
+        options.desugaredLibrarySpecification.getEmulateLibraryInterface().keySet());
   }
 
   public DexApplication prune(DexApplication app, PrefixRewritingMapper rewritePrefix) {
diff --git a/src/main/java/com/android/tools/r8/synthesis/SynthesizingContext.java b/src/main/java/com/android/tools/r8/synthesis/SynthesizingContext.java
index 9fe1fb9..bbf4258 100644
--- a/src/main/java/com/android/tools/r8/synthesis/SynthesizingContext.java
+++ b/src/main/java/com/android/tools/r8/synthesis/SynthesizingContext.java
@@ -132,7 +132,7 @@
     DexType rewrittenContext =
         appView
             .options()
-            .desugaredLibraryConfiguration
+            .desugaredLibrarySpecification
             .getEmulateLibraryInterface()
             .get(synthesizingContextType);
     if (rewrittenContext == null) {
diff --git a/src/main/java/com/android/tools/r8/utils/InternalOptions.java b/src/main/java/com/android/tools/r8/utils/InternalOptions.java
index dbeefb7..b67a8c2 100644
--- a/src/main/java/com/android/tools/r8/utils/InternalOptions.java
+++ b/src/main/java/com/android/tools/r8/utils/InternalOptions.java
@@ -53,7 +53,7 @@
 import com.android.tools.r8.horizontalclassmerging.Policy;
 import com.android.tools.r8.inspector.internal.InspectorImpl;
 import com.android.tools.r8.ir.code.IRCode;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
 import com.android.tools.r8.ir.desugar.nest.Nest;
 import com.android.tools.r8.ir.optimize.Inliner;
 import com.android.tools.r8.ir.optimize.enums.EnumDataMap;
@@ -385,8 +385,8 @@
     if (isGeneratingDex() || desugarState == DesugarState.ON) {
       marker.setMinApi(getMinApiLevel().getLevel());
     }
-    if (desugaredLibraryConfiguration.getIdentifier() != null) {
-      marker.setDesugaredLibraryIdentifiers(desugaredLibraryConfiguration.getIdentifier());
+    if (desugaredLibrarySpecification.getIdentifier() != null) {
+      marker.setDesugaredLibraryIdentifiers(desugaredLibrarySpecification.getIdentifier());
     }
     if (Version.isDevelopmentVersion()) {
       marker.setSha1(VersionProperties.INSTANCE.getSha());
@@ -433,7 +433,7 @@
   }
 
   public boolean isDesugaredLibraryCompilation() {
-    return desugaredLibraryConfiguration.isLibraryCompilation();
+    return desugaredLibrarySpecification.isLibraryCompilation();
   }
 
   public boolean isRelocatorCompilation() {
@@ -879,8 +879,8 @@
 
   // If null, no desugaring of library is performed.
   // If non null it contains flags describing library desugaring.
-  public DesugaredLibraryConfiguration desugaredLibraryConfiguration =
-      DesugaredLibraryConfiguration.empty();
+  public LegacyDesugaredLibrarySpecification desugaredLibrarySpecification =
+      LegacyDesugaredLibrarySpecification.empty();
 
   public boolean relocatorCompilation = false;
 
diff --git a/src/test/java/com/android/tools/r8/D8CommandTest.java b/src/test/java/com/android/tools/r8/D8CommandTest.java
index cd1ee66..9740064 100644
--- a/src/test/java/com/android/tools/r8/D8CommandTest.java
+++ b/src/test/java/com/android/tools/r8/D8CommandTest.java
@@ -634,7 +634,7 @@
   public void desugaredLibrary() throws CompilationFailedException {
     D8Command d8Command = parse("--desugared-lib", "src/library_desugar/desugar_jdk_libs.json");
     assertFalse(
-        d8Command.getInternalOptions().desugaredLibraryConfiguration.getRewritePrefix().isEmpty());
+        d8Command.getInternalOptions().desugaredLibrarySpecification.getRewritePrefix().isEmpty());
   }
 
   @Test
diff --git a/src/test/java/com/android/tools/r8/D8TestBuilder.java b/src/test/java/com/android/tools/r8/D8TestBuilder.java
index b2bf2e8..1c74df5 100644
--- a/src/test/java/com/android/tools/r8/D8TestBuilder.java
+++ b/src/test/java/com/android/tools/r8/D8TestBuilder.java
@@ -90,8 +90,8 @@
   public D8TestBuilder enableCoreLibraryDesugaring(
       AndroidApiLevel minApiLevel,
       KeepRuleConsumer keepRuleConsumer,
-      StringResource desugaredLibraryConfiguration) {
-    super.enableCoreLibraryDesugaring(minApiLevel, keepRuleConsumer, desugaredLibraryConfiguration);
+      StringResource desugaredLibrarySpecification) {
+    super.enableCoreLibraryDesugaring(minApiLevel, keepRuleConsumer, desugaredLibrarySpecification);
     return self();
   }
 
diff --git a/src/test/java/com/android/tools/r8/L8CommandTest.java b/src/test/java/com/android/tools/r8/L8CommandTest.java
index eb44743..e1902f4 100644
--- a/src/test/java/com/android/tools/r8/L8CommandTest.java
+++ b/src/test/java/com/android/tools/r8/L8CommandTest.java
@@ -246,7 +246,7 @@
   }
 
   @Test(expected = CompilationFailedException.class)
-  public void desugaredLibraryConfigurationRequired() throws Throwable {
+  public void desugaredLibrarySpecificationRequired() throws Throwable {
     DiagnosticsChecker.checkErrorsContains(
         "L8 requires a desugared library configuration",
         (handler) ->
@@ -357,7 +357,7 @@
     L8Command l8Command =
         parse("--desugared-lib", ToolHelper.getDesugarLibJsonForTesting().toString());
     assertFalse(
-        l8Command.getInternalOptions().desugaredLibraryConfiguration.getRewritePrefix().isEmpty());
+        l8Command.getInternalOptions().desugaredLibrarySpecification.getRewritePrefix().isEmpty());
   }
 
   private void checkSingleForceAllAssertion(
diff --git a/src/test/java/com/android/tools/r8/L8TestBuilder.java b/src/test/java/com/android/tools/r8/L8TestBuilder.java
index e672f87..f2b9a34 100644
--- a/src/test/java/com/android/tools/r8/L8TestBuilder.java
+++ b/src/test/java/com/android/tools/r8/L8TestBuilder.java
@@ -40,7 +40,7 @@
   private Consumer<InternalOptions> optionsModifier = ConsumerUtils.emptyConsumer();
   private Path desugarJDKLibs = ToolHelper.getDesugarJDKLibs();
   private Path desugarJDKLibsConfiguration = null;
-  private StringResource desugaredLibraryConfiguration =
+  private StringResource desugaredLibrarySpecification =
       StringResource.fromFile(ToolHelper.getDesugarLibJsonForTesting());
   private List<Path> libraryFiles = new ArrayList<>();
 
@@ -130,12 +130,12 @@
   }
 
   public L8TestBuilder setDesugaredLibraryConfiguration(Path path) {
-    this.desugaredLibraryConfiguration = StringResource.fromFile(path);
+    this.desugaredLibrarySpecification = StringResource.fromFile(path);
     return this;
   }
 
   public L8TestBuilder setDesugaredLibraryConfiguration(StringResource configuration) {
-    this.desugaredLibraryConfiguration = configuration;
+    this.desugaredLibrarySpecification = configuration;
     return this;
   }
 
@@ -148,7 +148,7 @@
             .addProgramFiles(getProgramFiles())
             .addLibraryFiles(getLibraryFiles())
             .setMode(mode)
-            .addDesugaredLibraryConfiguration(desugaredLibraryConfiguration)
+            .addDesugaredLibraryConfiguration(desugaredLibrarySpecification)
             .setMinApiLevel(apiLevel.getLevel())
             .setProgramConsumer(
                 backend.isCf()
diff --git a/src/test/java/com/android/tools/r8/LibraryDesugaringTestConfiguration.java b/src/test/java/com/android/tools/r8/LibraryDesugaringTestConfiguration.java
index d79f4af..0758bf7 100644
--- a/src/test/java/com/android/tools/r8/LibraryDesugaringTestConfiguration.java
+++ b/src/test/java/com/android/tools/r8/LibraryDesugaringTestConfiguration.java
@@ -66,7 +66,7 @@
   private final AndroidApiLevel minApiLevel;
   private final Path desugarJdkLibs;
   private final Path customConversions;
-  private final List<StringResource> desugaredLibraryConfigurationResources;
+  private final List<StringResource> desugaredLibrarySpecificationResources;
   private final boolean withKeepRuleConsumer;
   private final KeepRuleConsumer keepRuleConsumer;
   private final CompilationMode mode;
@@ -81,7 +81,7 @@
     this.customConversions = null;
     this.keepRuleConsumer = null;
     this.withKeepRuleConsumer = false;
-    this.desugaredLibraryConfigurationResources = null;
+    this.desugaredLibrarySpecificationResources = null;
     this.mode = null;
     this.addRunClassPath = false;
   }
@@ -90,7 +90,7 @@
       AndroidApiLevel minApiLevel,
       Path desugarJdkLibs,
       Path customConversions,
-      List<StringResource> desugaredLibraryConfigurationResources,
+      List<StringResource> desugaredLibrarySpecificationResources,
       boolean withKeepRuleConsumer,
       KeepRuleConsumer keepRuleConsumer,
       CompilationMode mode,
@@ -98,7 +98,7 @@
     this.minApiLevel = minApiLevel;
     this.desugarJdkLibs = desugarJdkLibs;
     this.customConversions = customConversions;
-    this.desugaredLibraryConfigurationResources = desugaredLibraryConfigurationResources;
+    this.desugaredLibrarySpecificationResources = desugaredLibrarySpecificationResources;
     this.withKeepRuleConsumer = withKeepRuleConsumer;
     this.keepRuleConsumer = keepRuleConsumer;
     this.mode = mode;
@@ -110,7 +110,7 @@
     AndroidApiLevel minApiLevel;
     private Path desugarJdkLibs;
     private Path customConversions;
-    private final List<StringResource> desugaredLibraryConfigurationResources = new ArrayList<>();
+    private final List<StringResource> desugaredLibrarySpecificationResources = new ArrayList<>();
     boolean withKeepRuleConsumer = false;
     KeepRuleConsumer keepRuleConsumer;
     private CompilationMode mode = CompilationMode.DEBUG;
@@ -126,8 +126,8 @@
     public Builder setConfiguration(Configuration configuration) {
       desugarJdkLibs = configuration.desugarJdkLibs;
       customConversions = configuration.customConversions;
-      desugaredLibraryConfigurationResources.clear();
-      desugaredLibraryConfigurationResources.add(
+      desugaredLibrarySpecificationResources.clear();
+      desugaredLibrarySpecificationResources.add(
           StringResource.fromFile(configuration.configuration));
       return this;
     }
@@ -147,8 +147,8 @@
       return this;
     }
 
-    public Builder addDesugaredLibraryConfiguration(StringResource desugaredLibraryConfiguration) {
-      desugaredLibraryConfigurationResources.add(desugaredLibraryConfiguration);
+    public Builder addDesugaredLibraryConfiguration(StringResource desugaredLibrarySpecification) {
+      desugaredLibrarySpecificationResources.add(desugaredLibrarySpecification);
       return this;
     }
 
@@ -163,8 +163,8 @@
     }
 
     public LibraryDesugaringTestConfiguration build() {
-      if (desugaredLibraryConfigurationResources.isEmpty()) {
-        desugaredLibraryConfigurationResources.add(
+      if (desugaredLibrarySpecificationResources.isEmpty()) {
+        desugaredLibrarySpecificationResources.add(
             StringResource.fromFile(ToolHelper.getDesugarLibJsonForTesting()));
       }
       if (withKeepRuleConsumer) {
@@ -174,7 +174,7 @@
           minApiLevel,
           desugarJdkLibs != null ? desugarJdkLibs : DEFAULT.desugarJdkLibs,
           customConversions != null ? customConversions : DEFAULT.customConversions,
-          desugaredLibraryConfigurationResources,
+          desugaredLibrarySpecificationResources,
           withKeepRuleConsumer,
           keepRuleConsumer,
           mode,
@@ -205,7 +205,7 @@
     if (keepRuleConsumer != null) {
       builder.setDesugaredLibraryKeepRuleConsumer(keepRuleConsumer);
     }
-    desugaredLibraryConfigurationResources.forEach(builder::addDesugaredLibraryConfiguration);
+    desugaredLibrarySpecificationResources.forEach(builder::addDesugaredLibraryConfiguration);
   }
 
   public void configure(R8Command.Builder builder) {
@@ -215,7 +215,7 @@
     if (keepRuleConsumer != null) {
       builder.setDesugaredLibraryKeepRuleConsumer(keepRuleConsumer);
     }
-    desugaredLibraryConfigurationResources.forEach(builder::addDesugaredLibraryConfiguration);
+    desugaredLibrarySpecificationResources.forEach(builder::addDesugaredLibraryConfiguration);
   }
 
   public Path buildDesugaredLibrary(TestState state) {
@@ -230,12 +230,12 @@
     }
     String finalGeneratedKeepRules = generatedKeepRules;
     try {
-      assert desugaredLibraryConfigurationResources.size() == 1 : "There can be only one";
+      assert desugaredLibrarySpecificationResources.size() == 1 : "There can be only one";
       return L8TestBuilder.create(minApiLevel, Backend.DEX, state)
           .addLibraryFiles(ToolHelper.getAndroidJar(AndroidApiLevel.P))
           .setDesugarJDKLibs(desugarJdkLibs)
           .setDesugarJDKLibsConfiguration(customConversions)
-          .setDesugaredLibraryConfiguration(desugaredLibraryConfigurationResources.get(0))
+          .setDesugaredLibraryConfiguration(desugaredLibrarySpecificationResources.get(0))
           .applyIf(
               mode == CompilationMode.RELEASE,
               builder -> {
diff --git a/src/test/java/com/android/tools/r8/R8CommandTest.java b/src/test/java/com/android/tools/r8/R8CommandTest.java
index 03f13ec..0b48fc2 100644
--- a/src/test/java/com/android/tools/r8/R8CommandTest.java
+++ b/src/test/java/com/android/tools/r8/R8CommandTest.java
@@ -765,7 +765,7 @@
   public void desugaredLibrary() throws CompilationFailedException {
     R8Command r8Command = parse("--desugared-lib", "src/library_desugar/desugar_jdk_libs.json");
     assertFalse(
-        r8Command.getInternalOptions().desugaredLibraryConfiguration.getRewritePrefix().isEmpty());
+        r8Command.getInternalOptions().desugaredLibrarySpecification.getRewritePrefix().isEmpty());
   }
 
   @Test
@@ -778,7 +778,7 @@
             "--desugared-lib-pg-conf-output",
             pgout.toString());
     assertFalse(
-        r8Command.getInternalOptions().desugaredLibraryConfiguration.getRewritePrefix().isEmpty());
+        r8Command.getInternalOptions().desugaredLibrarySpecification.getRewritePrefix().isEmpty());
   }
 
   @Test
diff --git a/src/test/java/com/android/tools/r8/R8TestBuilder.java b/src/test/java/com/android/tools/r8/R8TestBuilder.java
index 92270ae..1fa7630 100644
--- a/src/test/java/com/android/tools/r8/R8TestBuilder.java
+++ b/src/test/java/com/android/tools/r8/R8TestBuilder.java
@@ -666,8 +666,8 @@
   public T enableCoreLibraryDesugaring(
       AndroidApiLevel minApiLevel,
       KeepRuleConsumer keepRuleConsumer,
-      StringResource desugaredLibraryConfiguration) {
-    super.enableCoreLibraryDesugaring(minApiLevel, keepRuleConsumer, desugaredLibraryConfiguration);
+      StringResource desugaredLibrarySpecification) {
+    super.enableCoreLibraryDesugaring(minApiLevel, keepRuleConsumer, desugaredLibrarySpecification);
     return self();
   }
 
diff --git a/src/test/java/com/android/tools/r8/TestCompilerBuilder.java b/src/test/java/com/android/tools/r8/TestCompilerBuilder.java
index 4a6db32..a66a4b2 100644
--- a/src/test/java/com/android/tools/r8/TestCompilerBuilder.java
+++ b/src/test/java/com/android/tools/r8/TestCompilerBuilder.java
@@ -484,12 +484,12 @@
   public T enableCoreLibraryDesugaring(
       AndroidApiLevel minApiLevel,
       KeepRuleConsumer keepRuleConsumer,
-      StringResource desugaredLibraryConfiguration) {
+      StringResource desugaredLibrarySpecification) {
     return enableLibraryDesugaring(
         LibraryDesugaringTestConfiguration.builder()
             .setMinApi(minApiLevel)
             .setKeepRuleConsumer(keepRuleConsumer)
-            .addDesugaredLibraryConfiguration(desugaredLibraryConfiguration)
+            .addDesugaredLibraryConfiguration(desugaredLibrarySpecification)
             .dontAddRunClasspath()
             .build());
   }
diff --git a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/BufferedReaderTest.java b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/BufferedReaderTest.java
index f1ac89f..6b54606 100644
--- a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/BufferedReaderTest.java
+++ b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/BufferedReaderTest.java
@@ -10,8 +10,8 @@
 import com.android.tools.r8.StringResource;
 import com.android.tools.r8.TestParameters;
 import com.android.tools.r8.ToolHelper;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfigurationParser;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecificationParser;
 import com.android.tools.r8.utils.AndroidApiLevel;
 import com.android.tools.r8.utils.BooleanUtils;
 import com.android.tools.r8.utils.InternalOptions;
@@ -60,11 +60,11 @@
             : "Caught j$.io.UncheckedIOException");
   }
 
-  DesugaredLibraryConfiguration configurationAlternative3(
+  LegacyDesugaredLibrarySpecification configurationAlternative3(
       InternalOptions options, boolean libraryCompilation, TestParameters parameters) {
     // Parse the current configuration and amend the configuration for BufferedReader.lines. The
     // configuration is the same for both program and library.
-    return new DesugaredLibraryConfigurationParser(
+    return new LegacyDesugaredLibrarySpecificationParser(
             options.dexItemFactory(),
             options.reporter,
             libraryCompilation,
@@ -73,11 +73,11 @@
   }
 
   private void configurationForProgramCompilation(InternalOptions options) {
-    options.desugaredLibraryConfiguration = configurationAlternative3(options, false, parameters);
+    options.desugaredLibrarySpecification = configurationAlternative3(options, false, parameters);
   }
 
   private void configurationForLibraryCompilation(InternalOptions options) {
-    options.desugaredLibraryConfiguration = configurationAlternative3(options, true, parameters);
+    options.desugaredLibrarySpecification = configurationAlternative3(options, true, parameters);
   }
 
   @Test
@@ -143,7 +143,7 @@
         .addLibraryFiles(getLibraryFile())
         .addOptionsModification(
             options ->
-                options.desugaredLibraryConfiguration =
+                options.desugaredLibrarySpecification =
                     configurationAlternative3(options, false, parameters))
         .addInnerClasses(BufferedReaderTest.class)
         .setMinApi(parameters.getApiLevel())
@@ -172,7 +172,7 @@
         .addLibraryFiles(getLibraryFile())
         .addOptionsModification(
             options ->
-                options.desugaredLibraryConfiguration =
+                options.desugaredLibrarySpecification =
                     configurationAlternative3(options, false, parameters))
         .addInnerClasses(BufferedReaderTest.class)
         .addKeepMainRule(TestClass.class)
diff --git a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryCHMOnlyContentTest.java b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryCHMOnlyContentTest.java
index dc995e3..3e7d97d 100644
--- a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryCHMOnlyContentTest.java
+++ b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryCHMOnlyContentTest.java
@@ -8,8 +8,8 @@
 import com.android.tools.r8.TestParameters;
 import com.android.tools.r8.TestParametersCollection;
 import com.android.tools.r8.ToolHelper;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfigurationParser;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecificationParser;
 import com.android.tools.r8.utils.InternalOptions;
 import com.android.tools.r8.utils.codeinspector.CodeInspector;
 import java.nio.file.Path;
@@ -44,7 +44,7 @@
             false,
             Collections.emptyList(),
             options -> {
-              options.desugaredLibraryConfiguration =
+              options.desugaredLibrarySpecification =
                   chmOnlyConfiguration(options, true, parameters);
             });
     CodeInspector inspector = new CodeInspector(desugaredLib);
@@ -62,16 +62,16 @@
             true,
             Collections.emptyList(),
             options -> {
-              options.desugaredLibraryConfiguration =
+              options.desugaredLibrarySpecification =
                   chmOnlyConfiguration(options, true, parameters);
             });
     CodeInspector inspector = new CodeInspector(desugaredLib);
     assert inspector.clazz("j$.util.concurrent.ConcurrentHashMap").isPresent();
   }
 
-  DesugaredLibraryConfiguration chmOnlyConfiguration(
+  LegacyDesugaredLibrarySpecification chmOnlyConfiguration(
       InternalOptions options, boolean libraryCompilation, TestParameters parameters) {
-    return new DesugaredLibraryConfigurationParser(
+    return new LegacyDesugaredLibrarySpecificationParser(
             options.dexItemFactory(),
             options.reporter,
             libraryCompilation,
diff --git a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryConfigurationParsingTest.java b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryConfigurationParsingTest.java
index 2ef985e..efc5ce8 100644
--- a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryConfigurationParsingTest.java
+++ b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryConfigurationParsingTest.java
@@ -20,8 +20,8 @@
 import com.android.tools.r8.ToolHelper;
 import com.android.tools.r8.graph.DexItemFactory;
 import com.android.tools.r8.graph.DexType;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfigurationParser;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecificationParser;
 import com.android.tools.r8.origin.Origin;
 import com.android.tools.r8.utils.AbortException;
 import com.android.tools.r8.utils.AndroidApiLevel;
@@ -70,10 +70,11 @@
       ImmutableMap.<String, Object>builder()
           .put(
               "configuration_format_version",
-              DesugaredLibraryConfigurationParser.MAX_SUPPORTED_VERSION)
+              LegacyDesugaredLibrarySpecificationParser.MAX_SUPPORTED_VERSION)
           .put("group_id", "com.tools.android")
           .put("artifact_id", "desugar_jdk_libs")
-          .put("version", DesugaredLibraryConfigurationParser.MIN_SUPPORTED_VERSION.toString())
+          .put(
+              "version", LegacyDesugaredLibrarySpecificationParser.MIN_SUPPORTED_VERSION.toString())
           .put("required_compilation_api_level", 1)
           .put("synthesized_library_classes_package_prefix", "j$.")
           .put("common_flags", Collections.emptyList())
@@ -85,20 +86,20 @@
     return new LinkedHashMap<>(TEMPLATE);
   }
 
-  private DesugaredLibraryConfigurationParser parser(DiagnosticsHandler handler) {
-    return new DesugaredLibraryConfigurationParser(
+  private LegacyDesugaredLibrarySpecificationParser parser(DiagnosticsHandler handler) {
+    return new LegacyDesugaredLibrarySpecificationParser(
         factory, new Reporter(handler), libraryCompilation, minApi.getLevel());
   }
 
-  private DesugaredLibraryConfiguration runPassing(String resource) {
+  private LegacyDesugaredLibrarySpecification runPassing(String resource) {
     return runPassing(StringResource.fromString(resource, origin));
   }
 
-  private DesugaredLibraryConfiguration runPassing(StringResource resource) {
+  private LegacyDesugaredLibrarySpecification runPassing(StringResource resource) {
     TestDiagnosticMessagesImpl handler = new TestDiagnosticMessagesImpl();
-    DesugaredLibraryConfiguration config = parser(handler).parse(resource);
+    LegacyDesugaredLibrarySpecification spec = parser(handler).parse(resource);
     handler.assertNoMessages();
-    return config;
+    return spec;
   }
 
   private void runFailing(String json, Consumer<TestDiagnosticMessages> checker) {
@@ -114,9 +115,9 @@
   @Test
   public void testReference() throws Exception {
     // Just test that the reference file parses without issues.
-    DesugaredLibraryConfiguration config =
+    LegacyDesugaredLibrarySpecification spec =
         runPassing(StringResource.fromFile(ToolHelper.getDesugarLibJsonForTesting()));
-    assertEquals(libraryCompilation, config.isLibraryCompilation());
+    assertEquals(libraryCompilation, spec.isLibraryCompilation());
   }
 
   @Test
@@ -161,7 +162,7 @@
   @Test
   public void testUnsupportedVersion() {
     LinkedHashMap<String, Object> data = template();
-    SemanticVersion minVersion = DesugaredLibraryConfigurationParser.MIN_SUPPORTED_VERSION;
+    SemanticVersion minVersion = LegacyDesugaredLibrarySpecificationParser.MIN_SUPPORTED_VERSION;
     data.put(
         "version",
         new SemanticVersion(minVersion.getMajor(), minVersion.getMinor(), minVersion.getPatch() - 1)
@@ -255,15 +256,15 @@
                     "java.util.Foo", "j$.util.FooConv1",
                     "java.util.Foo2", "j$.util.FooConv2"))));
     // The gson parser will overwrite the key in order during parsing, thus hiding potential issues.
-    DesugaredLibraryConfiguration config = runPassing(toJson(data).replace("Foo2", "Foo"));
+    LegacyDesugaredLibrarySpecification spec = runPassing(toJson(data).replace("Foo2", "Foo"));
     assertEquals(
         Collections.singletonList("java.util.Foo"),
-        config.getCustomConversions().keySet().stream()
+        spec.getCustomConversions().keySet().stream()
             .map(DexType::toString)
             .collect(Collectors.toList()));
     assertEquals(
         Collections.singletonList("j$.util.FooConv2"),
-        config.getCustomConversions().values().stream()
+        spec.getCustomConversions().values().stream()
             .map(DexType::toString)
             .collect(Collectors.toList()));
   }
diff --git a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryMismatchTest.java b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryMismatchTest.java
index 91b87a0..1409ec7 100644
--- a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryMismatchTest.java
+++ b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryMismatchTest.java
@@ -14,7 +14,7 @@
 import com.android.tools.r8.StringResource;
 import com.android.tools.r8.TestParameters;
 import com.android.tools.r8.errors.DesugaredLibraryMismatchDiagnostic;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
 import com.android.tools.r8.origin.Origin;
 import com.android.tools.r8.utils.AndroidApiLevel;
 import com.android.tools.r8.utils.Box;
@@ -193,7 +193,7 @@
   public void testMergeDifferentLibraryDesugarVersions() throws Exception {
     // DEX code with library desugaring using a desugared library configuration with a
     // different identifier.
-    Box<DesugaredLibraryConfiguration> box = new Box<>();
+    Box<LegacyDesugaredLibrarySpecification> box = new Box<>();
     Path libraryDex =
         testForD8(Backend.DEX)
             .addProgramClasses(Library.class)
diff --git a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryTestBase.java b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryTestBase.java
index e57aaa9..d4a48f8 100644
--- a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryTestBase.java
+++ b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/DesugaredLibraryTestBase.java
@@ -24,8 +24,8 @@
 import com.android.tools.r8.ToolHelper;
 import com.android.tools.r8.ToolHelper.DexVm.Version;
 import com.android.tools.r8.errors.Unreachable;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfigurationParser;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecificationParser;
 import com.android.tools.r8.tracereferences.TraceReferences;
 import com.android.tools.r8.utils.AndroidApiLevel;
 import com.android.tools.r8.utils.FileUtils;
@@ -227,12 +227,12 @@
     return desugaredLib;
   }
 
-  protected DesugaredLibraryConfiguration configurationWithSupportAllCallbacksFromLibrary(
+  protected LegacyDesugaredLibrarySpecification configurationWithSupportAllCallbacksFromLibrary(
       InternalOptions options,
       boolean libraryCompilation,
       TestParameters parameters,
       boolean supportAllCallbacksFromLibrary) {
-    return new DesugaredLibraryConfigurationParser(
+    return new LegacyDesugaredLibrarySpecificationParser(
             options.dexItemFactory(),
             options.reporter,
             libraryCompilation,
diff --git a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/ExtractWrapperTypesTest.java b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/ExtractWrapperTypesTest.java
index 5c42b95..21dc2f9 100644
--- a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/ExtractWrapperTypesTest.java
+++ b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/ExtractWrapperTypesTest.java
@@ -16,8 +16,8 @@
 import com.android.tools.r8.ToolHelper;
 import com.android.tools.r8.graph.DexItemFactory;
 import com.android.tools.r8.graph.DexType;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfigurationParser;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecificationParser;
 import com.android.tools.r8.naming.MemberNaming.MethodSignature;
 import com.android.tools.r8.references.ClassReference;
 import com.android.tools.r8.references.MethodReference;
@@ -128,11 +128,11 @@
     CodeInspector desugaredApiJar = getDesugaredApiJar();
     Set<ClassReference> preDesugarTypes = getPreDesugarTypes();
 
-    DesugaredLibraryConfiguration conf = getDesugaredLibraryConfiguration();
+    LegacyDesugaredLibrarySpecification spec = getDesugaredLibraryConfiguration();
     Set<String> wrappersInSpec =
-        conf.getWrapperConversions().stream().map(DexType::toString).collect(Collectors.toSet());
+        spec.getWrapperConversions().stream().map(DexType::toString).collect(Collectors.toSet());
     Set<String> customConversionsInSpec =
-        conf.getCustomConversions().keySet().stream()
+        spec.getCustomConversions().keySet().stream()
             .map(DexType::toString)
             .collect(Collectors.toSet());
     assertEquals(
@@ -191,9 +191,9 @@
     return missingWrappers;
   }
 
-  private DesugaredLibraryConfiguration getDesugaredLibraryConfiguration() {
-    DesugaredLibraryConfigurationParser parser =
-        new DesugaredLibraryConfigurationParser(
+  private LegacyDesugaredLibrarySpecification getDesugaredLibraryConfiguration() {
+    LegacyDesugaredLibrarySpecificationParser parser =
+        new LegacyDesugaredLibrarySpecificationParser(
             new DexItemFactory(), null, true, minApi.getLevel());
     return parser.parse(StringResource.fromFile(ToolHelper.getDesugarLibJsonForTesting()));
   }
diff --git a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/InconsistentPrefixTest.java b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/InconsistentPrefixTest.java
index 43056e6..b1f57e1 100644
--- a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/InconsistentPrefixTest.java
+++ b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/InconsistentPrefixTest.java
@@ -10,7 +10,7 @@
 import com.android.tools.r8.TestBase;
 import com.android.tools.r8.TestParameters;
 import com.android.tools.r8.TestParametersCollection;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
 import com.android.tools.r8.jasmin.JasminBuilder;
 import java.nio.file.Path;
 import java.util.HashMap;
@@ -48,8 +48,8 @@
         .addProgramFiles(inputJar)
         .addOptionsModification(
             options ->
-                options.desugaredLibraryConfiguration =
-                    DesugaredLibraryConfiguration.withOnlyRewritePrefixForTesting(x, options))
+                options.desugaredLibrarySpecification =
+                    LegacyDesugaredLibrarySpecification.withOnlyRewritePrefixForTesting(x, options))
         .compileWithExpectedDiagnostics(
             diagnostics -> {
               diagnostics.assertErrorMessageThatMatches(
diff --git a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/LintFilesTest.java b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/LintFilesTest.java
index 283900e..18af69f 100644
--- a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/LintFilesTest.java
+++ b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/LintFilesTest.java
@@ -14,8 +14,8 @@
 import com.android.tools.r8.TestParametersCollection;
 import com.android.tools.r8.ToolHelper;
 import com.android.tools.r8.graph.DexItemFactory;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfigurationParser;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecificationParser;
 import com.android.tools.r8.utils.AndroidApiLevel;
 import com.android.tools.r8.utils.FileUtils;
 import com.android.tools.r8.utils.InternalOptions;
@@ -125,8 +125,8 @@
           directory.toString()
         });
     InternalOptions options = new InternalOptions(new DexItemFactory(), new Reporter());
-    DesugaredLibraryConfiguration desugaredLibraryConfiguration =
-        new DesugaredLibraryConfigurationParser(
+    LegacyDesugaredLibrarySpecification desugaredLibrarySpecification =
+        new LegacyDesugaredLibrarySpecificationParser(
                 options.itemFactory, options.reporter, false, AndroidApiLevel.B.getLevel())
             .parse(StringResource.fromFile(ToolHelper.getDesugarLibJsonForTesting()));
 
@@ -136,7 +136,7 @@
       }
       Path compileApiLevelDirectory = directory.resolve("compile_api_level_" + apiLevel.getLevel());
       if (apiLevel.getLevel()
-          < desugaredLibraryConfiguration.getRequiredCompilationApiLevel().getLevel()) {
+          < desugaredLibrarySpecification.getRequiredCompilationApiLevel().getLevel()) {
         System.out.println("!Checking " + compileApiLevelDirectory);
         continue;
       }
diff --git a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/ObjectsTest.java b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/ObjectsTest.java
index b2973f5..abdf5c5 100644
--- a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/ObjectsTest.java
+++ b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/ObjectsTest.java
@@ -15,8 +15,8 @@
 import com.android.tools.r8.TestParameters;
 import com.android.tools.r8.TestRuntime.CfVm;
 import com.android.tools.r8.ToolHelper;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfigurationParser;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecificationParser;
 import com.android.tools.r8.utils.AndroidApiLevel;
 import com.android.tools.r8.utils.BooleanUtils;
 import com.android.tools.r8.utils.InternalOptions;
@@ -84,9 +84,9 @@
         ToolHelper.getAndroidJar(Ordered.max(parameters.getApiLevel(), AndroidApiLevel.O));
   }
 
-  DesugaredLibraryConfiguration desugaredLibraryConfiguration(
+  LegacyDesugaredLibrarySpecification desugaredLibrarySpecification(
       InternalOptions options, boolean libraryCompilation, TestParameters parameters) {
-    return new DesugaredLibraryConfigurationParser(
+    return new LegacyDesugaredLibrarySpecificationParser(
             options.dexItemFactory(),
             options.reporter,
             libraryCompilation,
@@ -99,13 +99,13 @@
   }
 
   private void configurationForProgramCompilation(InternalOptions options) {
-    options.desugaredLibraryConfiguration =
-        desugaredLibraryConfiguration(options, false, parameters);
+    options.desugaredLibrarySpecification =
+        desugaredLibrarySpecification(options, false, parameters);
   }
 
   private void configurationForLibraryCompilation(InternalOptions options) {
-    options.desugaredLibraryConfiguration =
-        desugaredLibraryConfiguration(options, true, parameters);
+    options.desugaredLibrarySpecification =
+        desugaredLibrarySpecification(options, true, parameters);
   }
 
   private Matcher<MethodSubject> invokesObjectsCompare(String holder) {
diff --git a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/RetargetAndBackportTest.java b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/RetargetAndBackportTest.java
index 6b29a83..d077f3f 100644
--- a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/RetargetAndBackportTest.java
+++ b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/RetargetAndBackportTest.java
@@ -7,7 +7,7 @@
 import static org.junit.Assert.assertTrue;
 
 import com.android.tools.r8.TestParameters;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
 import com.android.tools.r8.origin.Origin;
 import com.android.tools.r8.utils.AndroidApiLevel;
 import com.android.tools.r8.utils.codeinspector.InstructionSubject;
@@ -53,8 +53,8 @@
         */
         .addOptionsModifier(
             options ->
-                options.desugaredLibraryConfiguration =
-                    DesugaredLibraryConfiguration.builder(
+                options.desugaredLibrarySpecification =
+                    LegacyDesugaredLibrarySpecification.builder(
                             options.dexItemFactory(), options.reporter, Origin.unknown())
                         .setDesugaredLibraryIdentifier("my-identifier")
                         .putRewritePrefix("java.time.", "j$.time.")
diff --git a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/conversiontests/AccessModeConversionTest.java b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/conversiontests/AccessModeConversionTest.java
index d392dd8..e242349 100644
--- a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/conversiontests/AccessModeConversionTest.java
+++ b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/conversiontests/AccessModeConversionTest.java
@@ -6,7 +6,7 @@
 
 import com.android.tools.r8.TestParameters;
 import com.android.tools.r8.desugar.desugaredlibrary.DesugaredLibraryTestBase;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
 import com.android.tools.r8.origin.Origin;
 import com.android.tools.r8.utils.AndroidApiLevel;
 import com.android.tools.r8.utils.BooleanUtils;
@@ -57,8 +57,8 @@
   }
 
   private void configureDesugaredLibrary(InternalOptions options, boolean l8Compilation) {
-    DesugaredLibraryConfiguration.Builder builder =
-        DesugaredLibraryConfiguration.builder(
+    LegacyDesugaredLibrarySpecification.Builder builder =
+        LegacyDesugaredLibrarySpecification.builder(
                 options.itemFactory, options.reporter, Origin.unknown())
             .setDesugaredLibraryIdentifier("com.tools.android:desugar_jdk_libs:9.99.99")
             .putRewritePrefix("java.nio.file.AccessMode", "j$.nio.file.AccessMode")
@@ -66,7 +66,7 @@
     if (l8Compilation) {
       builder.setLibraryCompilation();
     }
-    options.desugaredLibraryConfiguration = builder.build();
+    options.desugaredLibrarySpecification = builder.build();
   }
 
   @Test
diff --git a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/conversiontests/ConversionIntroduceInterfaceMethodTest.java b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/conversiontests/ConversionIntroduceInterfaceMethodTest.java
index a205079..aa97e55 100644
--- a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/conversiontests/ConversionIntroduceInterfaceMethodTest.java
+++ b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/conversiontests/ConversionIntroduceInterfaceMethodTest.java
@@ -87,7 +87,7 @@
         .enableCoreLibraryDesugaring(parameters.getApiLevel(), keepRuleConsumer)
         .addOptionsModification(
             opt ->
-                opt.desugaredLibraryConfiguration =
+                opt.desugaredLibrarySpecification =
                     configurationWithSupportAllCallbacksFromLibrary(
                         opt, false, parameters, supportAllCallbacksFromLibrary))
         .compile()
@@ -151,7 +151,7 @@
         .enableCoreLibraryDesugaring(parameters.getApiLevel(), keepRuleConsumer)
         .addOptionsModification(
             opt ->
-                opt.desugaredLibraryConfiguration =
+                opt.desugaredLibrarySpecification =
                     configurationWithSupportAllCallbacksFromLibrary(
                         opt, false, parameters, supportAllCallbacksFromLibrary))
         .compile()
diff --git a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/conversiontests/DuplicateAPIDesugaredLibTest.java b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/conversiontests/DuplicateAPIDesugaredLibTest.java
index 1fa4a7c..6b7d86e 100644
--- a/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/conversiontests/DuplicateAPIDesugaredLibTest.java
+++ b/src/test/java/com/android/tools/r8/desugar/desugaredlibrary/conversiontests/DuplicateAPIDesugaredLibTest.java
@@ -71,7 +71,7 @@
                         this.buildDesugaredLibrary(
                             api,
                             opt ->
-                                opt.desugaredLibraryConfiguration =
+                                opt.desugaredLibrarySpecification =
                                     configurationWithSupportAllCallbacksFromLibrary(
                                         opt, true, parameters, supportAllCallbacksFromLibrary)));
                     return desugaredLibBox.get();
diff --git a/src/test/java/com/android/tools/r8/memberrebinding/b135627418/B135627418.java b/src/test/java/com/android/tools/r8/memberrebinding/b135627418/B135627418.java
index 06a87e4..f3103f1 100644
--- a/src/test/java/com/android/tools/r8/memberrebinding/b135627418/B135627418.java
+++ b/src/test/java/com/android/tools/r8/memberrebinding/b135627418/B135627418.java
@@ -12,7 +12,7 @@
 import com.android.tools.r8.TestBase;
 import com.android.tools.r8.TestParameters;
 import com.android.tools.r8.TestParametersCollection;
-import com.android.tools.r8.ir.desugar.desugaredlibrary.DesugaredLibraryConfiguration;
+import com.android.tools.r8.ir.desugar.desugaredlibrary.legacyspecification.LegacyDesugaredLibrarySpecification;
 import com.android.tools.r8.memberrebinding.b135627418.library.Drawable;
 import com.android.tools.r8.memberrebinding.b135627418.library.DrawableWrapper;
 import com.android.tools.r8.memberrebinding.b135627418.library.InsetDrawable;
@@ -76,8 +76,8 @@
             .setMinApi(parameters.getRuntime())
             .addOptionsModification(
                 options ->
-                    options.desugaredLibraryConfiguration =
-                        DesugaredLibraryConfiguration.withOnlyRewritePrefixForTesting(
+                    options.desugaredLibrarySpecification =
+                        LegacyDesugaredLibrarySpecification.withOnlyRewritePrefixForTesting(
                             ImmutableMap.of(packageName + ".runtime", packageName + ".library"),
                             options))
             .compile();