@Override
    public void execute(Runnable command) {
        ObjectUtil.checkNotNull(command, "command").run();
    }
@Test
    public void testExecuteNonNullRunnable() throws Exception {
        FutureTask<Void> task = new FutureTask<Void>(new Runnable() {
            @Override
            public void run() {
                // NOOP
            }
        }, null);
        ImmediateExecutor.INSTANCE.execute(task);
        assertTrue(task.isDone());
        assertFalse(task.isCancelled());
        assertNull(task.get());
    }