### Question:
SentinelApacheHttpClientConfig { public void setExtractor(ApacheHttpClientResourceExtractor extractor) { AssertUtil.notNull(extractor, "extractor cannot be null"); this.extractor = extractor; }  String getPrefix(); void setPrefix(String prefix); ApacheHttpClientResourceExtractor getExtractor(); void setExtractor(ApacheHttpClientResourceExtractor extractor); ApacheHttpClientFallback getFallback(); void setFallback(ApacheHttpClientFallback fallback);  }### Answer:
@Test(expected = IllegalArgumentException.class) public void testConfigSetCleaner() { SentinelApacheHttpClientConfig config = new SentinelApacheHttpClientConfig(); config.setExtractor(null); }