@Override
 protected void readInternal(ObjectDataInput in) throws IOException {
   int mapSize = in.readInt();
   migrationData = new HashMap<String, QueueContainer>(mapSize);
   for (int i = 0; i < mapSize; i++) {
     String name = in.readUTF();
     QueueContainer container = new QueueContainer(name);
     container.readData(in);
     migrationData.put(name, container);
   }
 }