Fix tests

Change-Id: I2490585f884ccf5bc68ec98642866321d2b76094

src/main/java/com/android/tools/r8/ir/desugar/BackportedMethodRewriter.java

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 718084c..50b068c 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
@@ -489,9 +489,11 @@
   }
 
   private static DexType dispatchTypeFor(AppView<?> appView, DexMethod method, String suffix) {
+    String prefix =
+        appView.options().desugaredLibraryConfiguration.getSynthesizedLibraryClassesPackagePrefix();
     String descriptor =
         "L"
-            + appView.options().synthesizedClassPrefix
+            + prefix
             + UTILITY_CLASS_NAME_PREFIX
             + '$'
             + method.holder.getName()