public ReliableTopicConfig setExecutor(Executor executor) {
        this.executor = executor;
        return this;
    }
@Test
    public void setExecutor() {
        ReliableTopicConfig config = new ReliableTopicConfig("foo");

        Executor executor = mock(Executor.class);
        config.setExecutor(executor);

        assertSame(executor, config.getExecutor());

        config.setExecutor(null);

        assertNull(config.getExecutor());
    }