@Nonnull
            @Override
            public RegistrationAction onReply(@Nonnull ReqResMessage<Resp> reply) {
                promise.supply(reply.getBody());
                return RegistrationAction.STOP_LISTENING;
            }
Implements a {@link ReqRespChannel} using {@link ConversationChannel}s.

@param <Req> the request type
@param <Resp> the response type
helper/src/main/java/me/lucko/helper/messaging/reqresp/SimpleReqRespChannel.java