Aha! from Failure responses.

We know what to reply when everything runs smoothly. 

But, what should the return type be for fallbacks, What should the response be when something goes wrong ?

I was wondering and then Aha! 

All the response should packaged in DTOs . Yes All responses finally should look similar. 
This is obvious for some, but not for me. 

So i wanted to call a HTTP service wrapped in a circuitbreaker. which needs a fallback. 
So lo and behold i need to think .

GET /api/v1/product/{id} , suppose this service is shitty and is down. and i need a response. 

I want my own service to deal with it, say i get it from my cache only . 
so now. 

both response should be similar

ProductResponse{
    String id;
    String name;
    boolean error;
    String errorMsg;
}

so , now even if the service is down the recipent as to deal with similar response. and deal with it.,