It’s explicit in the responses you should expect for a given request, versus what you should expect. For example if the specification defined that a 404 is a va

It’s explicit in the responses you should expect for a given request, versus what you should expect. For example if the specification defined that a 404 is a valid use case then null or empty list is not considered an exception, but if it isn’t defined in the spec and you receive a 404 unexpectedly, then you can treat it as an exception rather than a valid response.