[Retrace] Add @Override to overriding method

Change-Id: I56f41f291f7138f1452c2457eff837928bfaa9fe
diff --git a/src/main/java/com/android/tools/r8/retrace/internal/ProguardMappingProviderImpl.java b/src/main/java/com/android/tools/r8/retrace/internal/ProguardMappingProviderImpl.java
index 04abae0..8ea72fa 100644
--- a/src/main/java/com/android/tools/r8/retrace/internal/ProguardMappingProviderImpl.java
+++ b/src/main/java/com/android/tools/r8/retrace/internal/ProguardMappingProviderImpl.java
@@ -19,6 +19,7 @@
     this.classNameMapper = classNameMapper;
   }
 
+  @Override
   ClassNameMapper getClassNameMapper() {
     return classNameMapper;
   }