Automatic merge from submit-queue

Fields with omitempty tag should still be considered as optional

We've added an "+optional" tag while ago for optional fields. Before that OpenAPI spec generated assumed all fields with "omitempty" in their json tags are optional. This should be still the case (as well as +optional tag) until these two things happen:

- We update all documentation asking developers to use +optional (My bad, I should have added this after the +optional PR)
- We fix swagger 1.2 spec generator to use +optional instead of omitempty.

Fixes #37149