OpenAPI: Mandatory properties of an Optional Property - node.js

Question

Pretty much what the title says. I have an optional object in the request body. However, if that object is given, it should mandatorily contain a few child properties.
My OpenAPI component config looks like this:
UserDetails:
type: object
properties:
surname:
type: string
givenName:
type: string
dob:
type: string
format: date
gender:
type: string
enum:
- male
- female
- others
partner:
type: object
properties:
name:
type: string
phone:
type: string
maxLength: 10
minLength: 10
pattern: ^[1-9]+[0-9]{9}$
required: [name, phone]
required:
- surname
- givenName
- dob
I am using express-openapi-validator to validate this. Now, I don't understand if this is the problem of the express-openapi-validator package or not, but the required fields (name, phone) of the optional field (partner) is never validated. I can just provide partner: {} and it slips in right through, or even, partner: { name: 'some name', phone: '123' }. Phone number should be validated for the length and the regex.
Am I missing anything in the definition?

Answer 1

There does not seem to be a solution to this, but I am closing this just for peace to my mind.
like what #Helen has replied, this seems to be an issue with the library itself.
In the process of developing my application, I discovered more problems, which make the the library express-openapi-validator and another library swagger-express-middleware I used, even lesser reliable for validating requests.
The other problem that I discovered was that a value is validated with a provided enum only if it is provided as an array:
eg. The following is validated correctly:
UserLiabilities:
type: object
properties:
liabilities:
type: object
properties:
creditCards:
type: array
items:
allOf:
- $ref: '#/components/schemas/Provider'
- type: object
properties:
limit:
type: number
minimum: 0
Here Provider is:
Provider:
type: object
properties:
provider:
type: string
enum: ['ABC', 'DEF', 'GHI', 'Others']
However, if I need provider as a plain string in an object (not in an array like above), it is not validated. And, it allows any arbitrary string:
homeLoan:
allOf:
- $ref: '#/components/schemas/Provider'
- type: object
properties:
amount:
type: number
minimum: 0
This behavior is consistent with atleast two libraries that I have tried and mentioned above. I am not sure I am doing something wrong here, but I have lost enough time trying to debug this and had to finally resolve this in my server itself.