ORM: is it possible to preserve NULL with serializeJSON()?

language
1 
a = {
  key = null
}
dump(serializeJSON(a))

will output:

{"key":null}

But if a is an ORM entity, then serializeJSON(a) will output:

{}

Is it possible to make serializeJSON() output null for an Entity?

Otherwise I have to check the existence of an Entity’s attribute (or column) before using it. It’s tedious and doesn’t make sense.

Thanks!