@Override
        public Void call() throws Exception {
            String failure = "";
            try {
                worker.taskWorker.stop(platform);
            } catch (Exception exception) {
                log.error("{}: worker.stop() exception", nodeName, exception);
                failure = exception.getMessage();
            }
            stateChangeExecutor.submit(new CompleteWorker(worker, failure));
            return null;
        }
Cleans up the resources associated with a worker.  Processed by the worker
cleanup thread pool.
trogdor/src/main/java/org/apache/kafka/trogdor/agent/WorkerManager.java