enhancement for event of response (follow up for pull request #3043)

[beiwei30]

This change now looks good to me.

It looks like we should do the same thing for response, change

            if ((flag & FLAG_EVENT) != 0) {
                res.setEvent(Response.HEARTBEAT_EVENT);
            }

to

            if ((flag & FLAG_EVENT) != 0) {
                res.setEvent(true);
            }

Originally posted by @beiwei30 in #3043

[CrazyHZM]

I will do it.

[CrazyHZM]

@beiwei30
I have submitted a pr fix it, please review it.