What is the best way to return different types of ResponseEntity in Spring MVC or Spring-Boot

Question

I have written simple rest application using Spring MVC 4 (or Spring-Boot). Within the controller I have return ResponseEntity. But in some cases I want to give

Answer 1

Its possible to return ResponseEntity without using generics, such as follows,

public ResponseEntity method() {
    boolean isValid = // some logic
    if (isValid){
        return new ResponseEntity(new Success(), HttpStatus.OK);
    }
    else{
        return new ResponseEntity(new Error(), HttpStatus.BAD_REQUEST);
    }
}