Warning cleanup in ChangeMergeQueue and MergeOp

Change-Id: I5a9f6e58cc7c25fbf77a7eafbb593faa161acc1d

gerrit-server/src/main/java/com/google/gerrit/server/git/ChangeMergeQueue.java

@@ -89,6 +89,7 @@ public class ChangeMergeQueue implements MergeQueue {
         });
       }
 
+      @SuppressWarnings("unused")
       @Provides
       public PerThreadRequestScope.Scoper provideScoper(
           final PerThreadRequestScope.Propagator propagator) {
@@ -243,6 +244,7 @@ public class ChangeMergeQueue implements MergeQueue {
       dest = d;
     }
 
+    @Override
     public void run() {
       unschedule(this);
       mergeImpl(dest);

gerrit-server/src/main/java/com/google/gerrit/server/git/MergeOp.java

@@ -487,6 +487,7 @@ public class MergeOp {
     toMerge.clear();
     toMerge.addAll(heads);
     Collections.sort(toMerge, new Comparator<CodeReviewCommit>() {
+      @Override
       public int compare(final CodeReviewCommit a, final CodeReviewCommit b) {
         return a.originalOrder - b.originalOrder;
       }
@@ -854,6 +855,7 @@ public class MergeOp {
       approvalList =
           db.patchSetApprovals().byPatchSet(n.patchsetId).toList();
       Collections.sort(approvalList, new Comparator<PatchSetApproval>() {
+        @Override
         public int compare(final PatchSetApproval a, final PatchSetApproval b) {
           return a.getGranted().compareTo(b.getGranted());
         }