Thanks for the transcription!

Surely Java can tell the difference between a key with a null value and the absence of that key, no?

I mean, you can set up your deserialization to handle nulls in different ways, but a string to object dictionary would capture this, right?

It can, but especially during serialization Java sometimes adds null references to null values.

That’s usually a mistake by the API designer and/or Java dev, but happens pretty often.

That’s exactly not the thing, because nobody broke the contract, they simply interpret it differently in details.

Having a null reference is perfectly valid json, as long as it’s not explicitly prohibited. Null just says “nothing in here” and that’s exactly what an omission also communicates.

The difference is just whether you treat implicit and explicit non-existence differently. And neither interpretation is wrong per contract.

Null means I’m telling you it’s null.

Omission means it’s not there and I’m not telling you anything about it.

There is a world of difference between those two statements. It’s the difference between telling someone you’re single or just sitting there and saying nothing.