@Override
                public void execute(final Runnable command) {
                    executor.execute(command);
                }
Anti-gentleman is not against villains, we believe that you are
providing a single-thread executor.

@param singleThreadExecutorService a {@link ExecutorService} instance
jraft-core/src/main/java/com/alipay/sofa/jraft/util/concurrent/DefaultSingleThreadExecutor.java