code: public void update(final byte[] key, final U value) {
      if ((key == null) || (key.length == 0)) { return; }
      insertOrIgnore(MurmurHash3.hash(key, DEFAULT_UPDATE_SEED)[0] >>> 1, value);
    }
docs: Updates this sketch with a byte[] key and U value.
  The value is passed to update() method of the Summary object associated with the key
  
  @param key The given byte[] key
  @param value The given U value