@Override
  public void toData(DataOutput out,
      SerializationContext context) throws IOException {
    super.toData(out, context);
    out.writeInt(bucketId);
  }
Sends a PartitionedRegion message to fetch all the entries for a bucketId

@param recipient the member that the fetch keys message is sent to
@param r the PartitionedRegion that contains the bucket
@param bucketId the identity of the bucket that contains the entries to be returned
@return the processor used to read the returned entries
@throws ForceReattemptException if the peer is no longer available
geode-core/src/main/java/org/apache/geode/internal/cache/partitioned/FetchEntriesMessage.java