private void completeDelayedReceives() {
        for (NetworkSend completedSend : completedSends) {
            Iterator<DelayedReceive> delayedReceiveIterator = delayedReceives.iterator();
            while (delayedReceiveIterator.hasNext()) {
                DelayedReceive delayedReceive = delayedReceiveIterator.next();
                if (delayedReceive.source().equals(completedSend.destinationId())) {
                    completedReceives.add(delayedReceive.receive());
                    delayedReceiveIterator.remove();
                }
            }
        }
    }
Simulate a server disconnect. This id will be present in {@link #disconnected()} on
the next {@link #poll(long)}.
clients/src/test/java/org/apache/kafka/test/MockSelector.java