private SofaResponse buildEmptyResponse(SofaRequest request) {
        SofaResponse response = new SofaResponse();
        Method method = request.getMethod();
        if (method != null) {
            response.setAppResponse(ClassUtils.getDefaultPrimitiveValue(method.getReturnType()));
        }
        return response;
    }
{@link HystrixCommand} for async requests

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