code: public final Http2FrameStream newStream() {
          Http2FrameCodec codec = frameCodec;
          if (codec == null) {
              throw new IllegalStateException(StringUtil.simpleClassName(Http2FrameCodec.class) + " not found." +
                      " Has the handler been added to a pipeline?");
          }
          return codec.newStream();
      }
docs: Creates a new {@link Http2FrameStream} object.
  
  <p>This method is <em>thread-safe</em>.