code: @Override
  	protected StringBuffer doPostProcessBundle(BundleProcessingStatus status, StringBuffer bundleData)
  			throws IOException {
  
  		if (jsEngine == null) {
  			initialize(status.getJawrConfig());
  		}
  
  		StopWatch stopWatch = new StopWatch();
  		stopWatch.start("Processing Autoprefixer on '" + status.getLastPathAdded() + "'");
  
  		String cssSource = bundleData.toString();
  		String res = null;
  		try {
  			res = (String) jsEngine.invokeFunction("process", cssSource, options);
  
  		} catch (NoSuchMethodException | ScriptException e) {
  			throw new BundlingProcessException(e);
  		}
  
  		stopWatch.stop();
  		if (PERF_LOGGER.isDebugEnabled()) {
  			PERF_LOGGER.debug(stopWatch.shortSummary());
  		}
  		return new StringBuffer(res);
  	}
docs: /*
  (non-Javadoc)
  
  @see net.jawr.web.resource.bundle.postprocess.
  AbstractChainedResourceBundlePostProcessor
  #doPostProcessBundle(net.jawr.web
  .resource.bundle.postprocess.BundleProcessingStatus,
  java.lang.StringBuffer)