Strengthening setup() contract

[Jeff Turner]

Hi,

Generator, Reader and Transformer all inherit from
SitemapModelComponent, which declares the setup() method:

public interface SitemapModelComponent extends Component {
    /**
     * Set the <code>SourceResolver</code>, objectModel
     * <code>Map</code>, the source and sitemap <code>Parameters</code>
     * used to process the request.
     */
    void setup(SourceResolver resolver, Map objectModel, String src, Parameters par)
        throws ProcessingException, SAXException, IOException;
}

If there's no objections, I would like to:
 - assert in the Javadoc that 'src' will never be null
 - modify AbstractProcessingPipeline to ensure this, and throw meaningful
   exceptions otherwise.

Currently, leaving out the 'src' attribute causes a typically unhelpful
Cocoon error message:

java.net.MalformedURLException: Invalid System ID

Strengthening this contract should at least improve the error message.


--Jeff