@Override
 protected void writeInternal(ObjectDataOutput out) throws IOException {
   super.writeInternal(out);
   out.writeObject(entryProcessor);
   out.writeInt(keys.size());
   for (Data key : keys) {
     out.writeData(key);
   }
 }
 @Override
 protected void writeInternal(ObjectDataOutput out) throws IOException {
   super.writeInternal(out);
   out.writeObject(entryProcessor);
 }