Description

Required fields that are specified in a oneOf are currently generated as required in the @JsonCreator constructor.

This incorrectly results in jackson MismatchedInputException when deserializing a valid json.

new ObjectMapper().readValue("{\"a\": 1}", Test.class);

Exception in thread "main" com.fasterxml.jackson.databind.exc.MismatchedInputException: Missing required creator property 'b' (index 1)

openapi-generator version

7.11.0

OpenAPI declaration file content or url

components:
  schemas:
    Test:
      type: object
      oneOf:
        - $ref: "#/components/schemas/TypeA"
        - $ref: "#/components/schemas/TypeB"
    TypeA:
      type: object
      properties:
        a:
          type: integer
      required: [a]
    TypeB:
      type: object
      properties:
        b:
          type: integer
      required: [b]

Generates

  @JsonCreator
  public Test(
    @JsonProperty(required = true, value = "a") Integer a,
    @JsonProperty(required = true, value = "b") Integer b
  ) {
    this.a = a;
    this.b = b;
  }

Related issues/PRs

Seems similar to what's been reported in #20513 for kotlin. But in combination with #19578 introduced in 7.11.0 there is significant impact as it causes jackson validation errors at runtime.