code: public ChannelFuture writeOneOutbound(Object msg, ChannelPromise promise) {
          if (checkOpen(true)) {
              return write(msg, promise);
          }
          return checkException(promise);
      }
docs: Writes one message to the outbound of this {@link Channel} and does not flush it. This
  method is conceptually equivalent to {@link #write(Object, ChannelPromise)}.
  
  @see #writeOneInbound(Object, ChannelPromise)