@Override
  protected void decodePayload(byte[] pl) {
    final int flags = decodeInt(pl, 0);
    final byte[] data = new byte[pl.length - EXTRA_HDR_LEN];
    System.arraycopy(pl, EXTRA_HDR_LEN, data, 0, pl.length - EXTRA_HDR_LEN);
    GetsOperation.Callback gcb = (GetsOperation.Callback) getCallback();
    gcb.gotData(key, flags, responseCas, data);
    getCallback().receivedStatus(STATUS_OK);
  }
Length of the extra header stuff for a GET response.
src/main/java/net/spy/memcached/protocol/binary/GetsOperationImpl.java