code: @Override
  	public Future<?> buildAsync(final Callable<?> builder, final HttpServletRequest req) {
  		return getExecutors().getBuildExecutor().submit(new Callable<Object>() {
  			public Object call() throws Exception {
  				AbstractAggregatorImpl.this.currentRequest.set(req);
  				Object result;
  				try {
  					result = builder.call();
  				} finally {
  					AbstractAggregatorImpl.this.currentRequest.set(null);
  				}
  				return result;
  			}
  		});
  	}
docs: /* (non-Javadoc)
  @see com.ibm.jaggr.core.IAggregator#buildAsync(java.util.concurrent.Callable, javax.servlet.http.HttpServletRequest)