Aggregator should not fail on OpenAPI specs with no definition or Path

[kubernetes]

Aggregator should not fail on OpenAPI specs with no definition or Path

[mbohlool]

Look like path is a required field in OpenAPI spec. We should, however, return an error here when Paths is nil (interesting that Paths is a pointer when it shouldn't be).

[roycaihw]

/assign
/unassign @mbohlool

[roycaihw]

Surprisingly Paths is required in OpenAPI spec but may be empty, due to ACL constraints. We already have some code allowing that

kube-openapi/pkg/aggregator/aggregator.go

Lines 187 to 189 in f08db29

	if orgPaths == nil {
	return
	}

Since the code in this repo makes little to no assumption about the routes that users may serve in OpenAPI spec, I vote for allowing empty Paths/PathItem instead of failing