Define how contains interacts with unevaluatedProperties

[jdesrosiers]

We recently (#1092) added support for contains to apply to objects, but we neglected to define how contains interacts with unevaluatedProperties. It should be consistent with how unevaluatedItems works.

Example

{
  "allOf": [
    {
      "type": "object",
      "contains": { "type": "number" }
    }
  ],
  "unevaluatedProperties": { "type": "boolean" }
}

{ "a": 1, "b": 2, "c": "NaN" }

Given this schema and instance, we should expect properties "a" and "b" to be "evaluated" and "c" to be unevaluated. "c" should be validated against the unevaluatedProperties schema and fail because it's not a boolean. However, currently unevaluatedProperties is only defined in terms of properties, patternProperties, additionalProperties, and itself, so contains doesn't create the relevant annotations and all of the properties will be considered unevaluated.

I'll create a PR soon to bring this in sync with the unevaluatedItems behavior.

[karenetheridge]

That brings in an inconsistency between items (né additionalItems) and additionalProperties. We used to see additionalItems and additionalItems as more or less analogues of each other, with the main difference being that the "index" of an object is a property name rather than an integer, and items are ordered and properties are not. If the application of contains to object properties will negate the application of additionalProperties to those properties, shouldn't applying contains to array items negate the application of items to those items as well?

Does it ever make sense to have contains as a sibling keyword to additionalProperties?

I wonder if we should re-evaluate the interaction of these keywords at the same time as the consideration of how unevaluatedProperties and unevaluatedItems interacts with evaluated-but-not-successfully properties/items in json-schema-org/community#67.

[jdesrosiers]

@karenetheridge I was so confused by your comment and I think I just figured out why. I used additionalProperties in the issue description instead of unevaluatedProperties. This change should have no effect on additionalProperties. It should only affect how contains interacts with unevaluatedProperties. Does that clear things up? Or am I still missing something?

[karenetheridge]

Yes, much better :D :D :D