code: public String getCacheName(CmsResource resource, Locale locale, String docTypeName) {
  
          // create a StringBuffer for the result
          StringBuffer buf = new StringBuffer(m_rfsRepository.length() + 36);
          buf.append(m_rfsRepository);
          buf.append('/');
          buf.append(resource.getResourceId().toString());
  
          if (docTypeName != null) {
              buf.append('_');
              buf.append(docTypeName);
          }
  
          // check if parameters are provided, if so add them as well
          if (locale != null) {
              buf.append('_');
              buf.append(locale.toString());
          }
  
          // append the date of last content modification to the result buffer
          // please note that we need only worry about last change in content, since properties are ignored here
          buf.append('_');
          buf.append(resource.getDateContent());
  
          // finally append the extension
          buf.append(".ext");
          return buf.toString();
      }
docs: Returns the RFS name used for caching an the text extraction result
  based on the given VFS resource and locale.<p>
  
  @param resource the VFS resource to generate the cache name for
  @param locale the locale to generate the cache name for (may be <code>null</code>)
  @param docTypeName the name of the search document type
  
  @return the RFS name to use for caching the given VFS resource with parameters