code: public static Payload create(CharSequence data, @Nullable CharSequence metadata) {
      return create(
          StandardCharsets.UTF_8.encode(CharBuffer.wrap(data)),
          metadata == null ? null : StandardCharsets.UTF_8.encode(CharBuffer.wrap(metadata)));
    }
docs: Static factory method for a text payload. Mainly looks better than "new DefaultPayload(data,
  metadata)"
  
  @param data the data of the payload.
  @param metadata the metadata for the payload.
  @return a payload.