Add missing override annotation in ProguardMapReaderWithFiltering

Change-Id: Ie5ca857552825d0e271f3f8a1752464f658b7738
diff --git a/src/main/java/com/android/tools/r8/retrace/internal/ProguardMapReaderWithFiltering.java b/src/main/java/com/android/tools/r8/retrace/internal/ProguardMapReaderWithFiltering.java
index 81fdd38..279a038 100644
--- a/src/main/java/com/android/tools/r8/retrace/internal/ProguardMapReaderWithFiltering.java
+++ b/src/main/java/com/android/tools/r8/retrace/internal/ProguardMapReaderWithFiltering.java
@@ -29,6 +29,7 @@
 
   public abstract boolean exceedsBuffer();
 
+  @Override
   public String readLine() throws IOException {
     byte[] bytes = readLineFromMultipleReads();
     if (bytes == null) {