@Override
  public String toString() {
    if (partitionedRegion != null) {
      String rName = partitionedRegion.getFullPath();
      return partitionedRegion.getMyId() + "@" + getClass().getName() + "@"
          + System.identityHashCode(this) + " name: " + rName + " bucket count: "
          + localBucket2RegionMap.size();
    }
    return null;
  }
Get the local keys for a given bucket. This operation should be as efficient as possible, by
avoiding making copies of the returned set. The returned set can and should reflect concurrent
changes (no ConcurrentModificationExceptions).

@param allowTombstones whether to include destroyed entries in the result
@return The <code>Set</code> of keys for bucketId or {@link Collections#EMPTY_SET} if no keys
        are present
@throws PRLocallyDestroyedException if the PartitionRegion is locally destroyed
geode-core/src/main/java/org/apache/geode/internal/cache/PartitionedRegionDataStore.java