Allow null as standalone type

[JurianArie]

The validator throws an exception with the following (API enforces that only one of the fields is filled):

Data passed:

[
    'department_id' => null,
    'team_id' => 1,
]

Schema:

- oneOf:
    - type: object
      properties:
        department_id:
          type: integer
        team_id:
          type: 'null'
      required:
        - department_id
    - type: object
      properties:
        department_id:
          type: 'null'
        team_id:
          type: integer
      required:
        - team_id

With the proposed change the validator would not throw an exception any more.

[leNEKO]

Hi, it seems that there is not a such null type in the openapi specification (see https://swagger.io/docs/specification/data-models/data-types/#null).

[JurianArie]

@leNEKO openapi 3.1 does have a "null" type: https://www.openapis.org/blog/2021/02/16/migrating-from-openapi-3-0-to-3-1-0 under the section "Swap nullable for type arrays"