require that responses object has 'default' or a response code (fixes #2833)

[karenetheridge]

ref. https://spec.openapis.org/oas/v3.1.0#responses-object

I realized that there is a way of saying "the patternProperties keyword must match something", by using a false in a conditional.

We decided in #2799 that a numeric response code was not required as long as default was present instead.

I tested it with the following test cases (using the format used by https://github.com/json-schema-org/JSON-Schema-Test-Suite).

[
{
"description": "openapi v3.1 test stuff",
"schema": {
"$defs": {
"specification-extensions": {
"patternProperties": {
"^x-": true
}
}
},
"type": "object",
"properties": {
"default": true
},
"patternProperties": {
"^[1-5](?:[0-9]{2}|XX)$": true
},
"minProperties": 1,
"$ref": "#/$defs/specification-extensions",
"unevaluatedProperties": false,
"$comment": "either default, or at least one response code property must exist",
"if": {
"patternProperties": {
"^[1-5](?:[0-9]{2}|XX)$": false
}
},
"then" : {
"required": [ "default" ]
}
},
"tests": [
{
"description": "one number property",
"data": { "400": true },
"valid": true
},
{
"description": "one number property and x-",
"data": { "400": true, "x-blah": 1 },
"valid": true
},
{
"description": "default property",
"data": { "default": true },
"valid": true
},
{
"description": "default property and x-",
"data": { "default": true, "x-blah": 1 },
"valid": true
},
{
"description": "one number property and x-, extra fields not permitted",
"data": { "400": true, "bloop": 1 },
"valid": false
},
{
"description": "one number property and x-, extra fields not permitted",
"data": { "400": true, "x-blah": 1, "bloop": 1 },
"valid": false
},
{
"description": "default property, extra fields not permitted",
"data": { "default": true, "bloop": 1 },
"valid": false
},
{
"description": "default property and x-",
"data": { "default": true, "x-blah": 1, "bloop": 1 },
"valid": false
},
{
"description": "no properties",
"data": {},
"valid": false
},
{
"description": "no required properties, with x-",
"data": { "x-blah": 1 },
"valid": false
},
{
"description": "no required properties, extra properties not permitted-",
"data": { "bloop": 1 },
"valid": false
}
]
}
]

[darrelmiller]

@OAI/tsc Can we get another approval and merge?

[MikeRalphson]

LGTM, thanks.