I'm afraid it's not enough to block sessionCreated() and
messageReceived(). I think all IoFilter methods except init() and
destroy(), filterWrite(), filterClose() and maybe exceptionCaught() will
have to be intercepted by BlacklistFilter and checked against the blacklist.
It would be nice if there are always consistency in what order the
IoHandler callbacks are called. E.g. sessionCreated is always called
first, then sessionOpened, then 0 or more messageReceived/messageSent
followed by sessionClosed. If only sessionCreated is blocked,
sessionOpened could be called first which could lead to strange bugs if
the Mina user uses sessionCreated to allocate resources etc.