New Method isUndefined

[MelleD]

Hey,

@cbornet convinced me, it's really better to use the JsonNullable instead of Optionals.
From the discussion here OpenAPITools/openapi-generator#3214, the question: Make it sense to create a new method isUndefined()

@JsonIgnore
public boolean isUndefined(){
    return UNDEFINED.equals(this);
}

Before i create a PR, is there a reason why we should not create this method?

[cbornet]

Glad I convinced you 😀. At first I thought that it wouldn't be necessary since we already have isPresent() but I see that Java 11 introduced isEmpty() for Optional so I guess we can do the same. It's probably nice to use it as method reference in filter operations.
About the implementation, I think it would be better to just return !isPresent.

[MelleD]

Maybe I misunderstood it, but how can you find out if the state is a "reset" or not?

Is the reset state a JsonNullable.of(null). So it's present but the value is null?

[cbornet]

If JsonNullable is in state "undefined", isPresent() returns false. Otherwise it returns true.
Why did you close ?

[MelleD]

Yes, then an extension for isUndefined would make more sense.

I adjust the title of the ticket.

[MelleD]

Hi @cbornet , PR is open :)