public void setVBucket(String k, short vb) {
    assert k.equals(key) : (k + " doesn't match the key " + key
        + " for this operation");
    vbucket = vb;
  }
Binary operations that contain a single key and are VBucket aware operations
should extend this class.
src/main/java/net/spy/memcached/protocol/binary/SingleKeyOperationImpl.java