code: @Override
      public void emitResponse(T response) {
          if (!isTerminated()) {
              subject.onNext(response);
              valueSet.set(true);
          } else {
              throw new IllegalStateException("Response has already terminated so response can not be set : " + response);
          }
      }
docs: Emit a response that should be OnNexted to an Observer
  @param response response to emit to initial command