ServerSample.java

public void start() throws NioHttpServerException {
    InputStream inputStream = inputStream();

    requestHandler
        .apply(inputStream)
        .toStream()
        .map(
            v -> {
              switch (v.status()) {
                case OK:
                  return Optional.of(v.getResult());
                case ERR:
                  return Optional.of(v.getError());
              }
              return Optional.empty();
            });
  }