readonly fields in parents generate invalid code with 'microprofile' generator

Description

When using allOff and having readonly fields in the parent, then the 'microprofile' generator creates a constructor that does not compile:

@JsonbCreator
public Child(
@JsonbProperty(value = "parentField") String parentField
) {
this.parentField = parentField; //As parentField is private, this is not allowed.
}

openapi-generator version

7.19.0

OpenAPI declaration file content or url

info:
  title: Reproduce
  version: 'v1'
components:
  schemas:
    Child:
      required:
        - childField1
      type: object
      allOf:
        - $ref: "#/components/schemas/Parent"
      properties:
        childField1:
          type: string

    Parent:
      required:
        - parentField
      type: object
      properties:
        parentField:
          type: string
          readOnly: true
      discriminator:
        propertyName: classType
        mapping:
          Child: "#/components/schemas/Child"
paths:
  '/v1/reproduce':
    get:
      responses:
        '200':
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Child'
          description: 'reproduce'

Generation Details

generatorName = "java"
library = "resteasy"
...

configOptions = [
        generatorName       : "java",
        library             : "microprofile",
]

Steps to reproduce

Just generate the code.

Related issues/PRs

#16374 but for generator 'resteasy'

Suggest a fix

The bug is caused by this line https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/Java/libraries/microprofile/pojo.mustache#L70.

A fix could be to either call the constructor in the superclass with the parents readonly fields, or by changing the access modifiers from 'private' to 'package' on the readonly parent fields.

Start with modules/openapi-generator/src/main/resources/Java/libraries/microprofile/pojo.mustache at the referenced line, then generate Java code from the provided OpenAPI declaration using the microprofile library. Check the Child constructor and Parent readonly field access in the generated output. Done means the generated code compiles without breaking the readonly parent-field behavior.