code: public I_CmsExtractionResult extractContent(CmsObject cms, CmsResource resource, I_CmsSearchIndex index)
      throws CmsIndexException {
  
          if (resource == null) {
              throw new CmsIndexException(Messages.get().container(Messages.ERR_NO_RAW_CONTENT_1, index.getLocale()));
          }
          // just return an empty result set
          return new CmsExtractionResult("");
      }
docs: Just returns an empty extraction result since the content can't be extracted form a generic resource.<p>
  
  @see org.opencms.search.documents.I_CmsSearchExtractor#extractContent(CmsObject, CmsResource, I_CmsSearchIndex)