When calling close on SseEventSink, it is possible to miss events that are still in the queue, because they are still waiting on output completion before being drained. Currently, the close method clears all events from the queue.

I noticed this by running the TCK on Quarkus, which sends the even in a try / close block. It seems the Vert.x writer gets deferred and in the meanwhile the close from the try kicks in and clears the events.