public GossipDigestAckMessage deserialize(DataInputStream dis) throws IOException {
   List<GossipDigest> gDigestList = GossipDigestSerializationHelper.deserialize(dis);
   dis.readBoolean(); // 0.6 compatibility
   Map<InetAddress, EndpointState> epStateMap = EndpointStatesSerializationHelper.deserialize(dis);
   return new GossipDigestAckMessage(gDigestList, epStateMap);
 }
 public void serialize(GossipDigestAckMessage gDigestAckMessage, DataOutputStream dos)
     throws IOException {
   GossipDigestSerializationHelper.serialize(gDigestAckMessage.gDigestList_, dos);
   dos.writeBoolean(true); // 0.6 compatibility
   EndpointStatesSerializationHelper.serialize(gDigestAckMessage.epStateMap_, dos);
 }