@Override
    protected SofaResponse getFallback() {
        return getFallback(null, getExecutionException());
    }
{@link HystrixCommand} for sync requests

@author <a href=mailto:scienjus@gmail.com>ScienJus</a>
fault/fault-hystrix/src/main/java/com/alipay/sofa/rpc/hystrix/SofaHystrixCommand.java