Gregsdennis/format registry

[gregsdennis]

What kind of change does this PR introduce?

Feature

Issue & Discussion References

Related to #1552

Summary

• Adds a format registry file and includes OpenAPI 3.1.1 formats. In the issue, I mocked up the registry with an array at the root, but realized an object would be good since we really shouldn't have multiple definitions for the same format. (I have other thoughts on this that I'll post in the issue and update here if necessary.)
• Adds text defining the registry and requirements for implementations to support them. Having a link to a later section feels weird to me. Maybe it's not? Happy to reorganize if others think it's off.

Does this PR introduce a breaking change?

No. There is a new "SHOULD" requirement to support the registry formats. I'd like this to be slightly less required than the ones defined by JSON Schema, but "MAY" seems not required enough. Open to entertaining ideas.

[ralfhandl]

@gregsdennis What about the formats registered in https://spec.openapis.org/registry/format/index.html?
Will they be eventually registered here, too?

And what will be the process/hurdles for registering formats?

Goal would be to retire the OAS format registry and instead redirect here.

[gregsdennis]

I didn't know that page existed. I was just looking at your spec.

Yeah, I expect those can be pulled in as well. The plan was to transfer your registry to us.

Given the sheer volume of formats, I'm more inclined to use "MAY" for the registry formats, but also reserve those names so that they can only mean what's registered. That way if those names are supported, they MUST be these formats.