Discord JDA ожидает MSG
EventWaiter waiter = new EventWaiter();
// SO wouldn't let me insert new lines for some reason.
waiter.waitForEvent(GuildMessageReceivedEvent.class, (event) -> event.getMessage().getContentRaw().equalsIgnoreCase("hello"), (event) -> event.getChannel().sendMessage("hello!").queue()));
Delightful Dingo