@Override
                    public void onException(Throwable e) {
                        logger.error("Process exception in callback.", e);
                        rets.add(e);
                        latch.countDown();
                    }
test async send back exception

@author xiaomin.cxm
@version $Id: BasicUsageTest.java, v 0.1 Apr 6, 2016 8:58:36 PM xiaomin.cxm Exp $
src/test/java/com/alipay/remoting/rpc/exception/BasicUsage_AsyncProcessor_Exception_Test.java