code: @Override
  	protected boolean isCacheValid() {
  
  		String cachedUrlMode = cacheProperties.getProperty(JawrConstant.SASS_GENERATOR_URL_MODE);
  		return super.isCacheValid() && StringUtils.equals(cachedUrlMode,
  				config.getProperty(JawrConstant.SASS_GENERATOR_URL_MODE, SASS_GENERATOR_DEFAULT_URL_MODE));
  	}
docs: /*
  (non-Javadoc)
  
  @see net.jawr.web.resource.bundle.generator.AbstractCachedGenerator#
  isCacheValid()