Add addtionalItemsContains and unevaluatedItemsContains keywords

[jdesrosiers]

This isn't a serious feature request at this point, but it occurred to me that this was something that JSON Schema is incapable of expressing, so I'm creating an issue to document the deficiency. I've never heard of anyone needing this feature, so it's probably better for someone to write a vocab for if they need it.

These keywords would work exactly like contains, but only apply to "additional items" as determined by additionalItems or unevaluatedItems.

Proposal

• Add keyword additionalItemsContains that works exactly like contains, but only applies to "additional items" as determined by the additionalItems keyword.
• Add keyword additionalItemsMaxContains that works exactly like maxContains, but only applies to "additional items" as determined by the additionalItems keyword.
• Add keyword additionalItemsMinContains that works exactly like minContains, but only applies to "additional items" as determined by the additionalItems keyword.
• Add keyword unevaluatedItemsContains that works exactly like contains, but only applies to "additional items" as determined by the unevaluatedItems keyword.
• Add keyword unevaluatedItemsMaxContains that works exactly like maxContains, but only applies to "additional items" as determined by the unevaluatedItems keyword.
• Add keyword unevaluatedItemsMinContains that works exactly like minContains, but only applies to "additional items" as determined by the unevaluatedItems keyword.

Pros

• Givens JSON Schema the ability to describe something it can't currently do.

Cons

• That's a lot of keywords to add for a feature that no one has ever asked for.

[handrews]

That's a lot of keywords to add for a feature that no one has ever asked for.

🤣

I'm going to go ahead and move this over to our vocabularies repo- we're doing that with most new keyword proposals now (although we haven't finished moving the ones that were filed in the past).