private void enqueueLast(CoordinatorEvent event) {
        try {
            processor.enqueueLast(event);
        } catch (RejectedExecutionException ex) {
            throw new NotCoordinatorException("Can't accept an event because the processor is closed", ex);
        }
    }
Enqueues a new event at the end of the processing queue.

@param event The event.
@throws NotCoordinatorException If the event processor is closed.
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/runtime/CoordinatorRuntime.java