NullResponseProcessor processor = new NullResponseProcessor();
        assertTrue(processor instanceof ResponseProcessor);
    }

    public void test_processWithValidResponseData() {
        // Test process method with valid ResponseData
        NullResponseProcessor processor = new NullResponseProcessor();
        ResponseData responseData = new ResponseData();

```

**Rule**: Pattern-based response routing (`RegexRule`, `SitemapsRule`)
**ResponseProcessor**: `DefaultResponseProcessor`, `SitemapsResponseProcessor`, `NullResponseProcessor`
**Transformer**: `HtmlTransformer`, `XmlTransformer`, `FileTransformer`, etc.
**Extractor**: Weight-based selection (tries in descending weight order)

### Key Extractors