public void setExtractor(ApacheHttpClientResourceExtractor extractor) {
        AssertUtil.notNull(extractor, "extractor cannot be null");
        this.extractor = extractor;
    }
@Test(expected = IllegalArgumentException.class)
    public void testConfigSetCleaner() {
        SentinelApacheHttpClientConfig config = new SentinelApacheHttpClientConfig();
        config.setExtractor(null);
    }