HADOOP-16472. findbugs warning on LocalMetadataStore.ttlTimeProvider sync

Contributed by Steve Loughran.

Moved the setter and addAncestors to synchronized

Change-Id: Ib362c66d1b8c9124eca7db9a44274ac08d0b3be6

hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/s3guard/LocalMetadataStore.java

@@ -605,12 +605,12 @@ public class LocalMetadataStore implements MetadataStore {
   }
 
   @Override
-  public void setTtlTimeProvider(ITtlTimeProvider ttlTimeProvider) {
+  public synchronized void setTtlTimeProvider(ITtlTimeProvider ttlTimeProvider) {
     this.ttlTimeProvider = ttlTimeProvider;
   }
 
   @Override
-  public void addAncestors(final Path qualifiedPath,
+  public synchronized void addAncestors(final Path qualifiedPath,
       @Nullable final BulkOperationState operationState) throws IOException {
 
     Collection<PathMetadata> newDirs = new ArrayList<>();