Use a set via ConcurrentHashMap.newKeySet instead of a map.

Change-Id: Iba6ed82225caca8cec1323c5b2f06281a04a5d56
diff --git a/src/test/java/com/android/tools/r8/compilerapi/desugardependencies/DesugarDependenciesTest.java b/src/test/java/com/android/tools/r8/compilerapi/desugardependencies/DesugarDependenciesTest.java
index d361457..2b83f85 100644
--- a/src/test/java/com/android/tools/r8/compilerapi/desugardependencies/DesugarDependenciesTest.java
+++ b/src/test/java/com/android/tools/r8/compilerapi/desugardependencies/DesugarDependenciesTest.java
@@ -14,7 +14,7 @@
 import com.android.tools.r8.compilerapi.CompilerApiTest;
 import com.android.tools.r8.compilerapi.CompilerApiTestRunner;
 import com.android.tools.r8.origin.Origin;
-import java.util.Map;
+import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import org.junit.Test;
 
@@ -57,16 +57,16 @@
               .setProgramConsumer(DexIndexedConsumer.emptyConsumer())
               .setDesugarGraphConsumer(
                   new DesugarGraphConsumer() {
-                    private final Map<Origin, Origin> desugaringUnit = new ConcurrentHashMap<>();
+                    private final Set<Origin> desugaringUnit = ConcurrentHashMap.newKeySet();
 
                     @Override
                     public void acceptProgramNode(Origin node) {
-                      desugaringUnit.put(node, node);
+                      desugaringUnit.add(node);
                     }
 
                     @Override
                     public void accept(Origin dependent, Origin dependency) {
-                      assertTrue(desugaringUnit.containsKey(dependent));
+                      assertTrue(desugaringUnit.contains(dependent));
                     }
 
                     @Override
diff --git a/src/test/java/com/android/tools/r8/desugar/graph/CompilationDependentSetTest.java b/src/test/java/com/android/tools/r8/desugar/graph/CompilationDependentSetTest.java
index 58fafe6..b0f6682 100644
--- a/src/test/java/com/android/tools/r8/desugar/graph/CompilationDependentSetTest.java
+++ b/src/test/java/com/android/tools/r8/desugar/graph/CompilationDependentSetTest.java
@@ -23,7 +23,7 @@
 public class CompilationDependentSetTest extends TestBase {
 
   public interface I {
-    // Emtpy.
+    // Empty.
   }
 
   public static class A implements I {
diff --git a/src/test/java/com/android/tools/r8/desugar/graph/InterfaceToImplementingClassDependencyTest.java b/src/test/java/com/android/tools/r8/desugar/graph/InterfaceToImplementingClassDependencyTest.java
index 705410a..6339195 100644
--- a/src/test/java/com/android/tools/r8/desugar/graph/InterfaceToImplementingClassDependencyTest.java
+++ b/src/test/java/com/android/tools/r8/desugar/graph/InterfaceToImplementingClassDependencyTest.java
@@ -33,7 +33,7 @@
   // Note: the dependency of I for the compilation of A exists even when no default methods do.
 
   public interface I {
-    // Emtpy.
+    // Empty.
   }
 
   public static class A implements I {