code: @Override
    public String hmset(final byte[] key, final Map<byte[], byte[]> hash) {
      checkIsInMultiOrPipeline();
      client.hmset(key, hash);
      return client.getStatusCodeReply();
    }
docs: Set the respective fields to the respective values. HMSET replaces old values with new values.
  <p>
  If key does not exist, a new key holding a hash is created.
  <p>
  <b>Time complexity:</b> O(N) (with N being the number of fields)
  @param key
  @param hash
  @return Always OK because HMSET can't fail