Swagger UI / Open API - type name lost when annotating property with @Schema(nullable = true)

[josephearl]

Describe the bug

Given the following resource response or request:

public class Parent {
  private Child firstChild;

  @Schema(nullable = true)
  private Child secondChild;

  public Child getFirstChild() {
    return firstChild;
  }

  public Child getSecondChild() {
    return secondChild;
  }
}

The schema in the documentation does not display the type name for secondChild as I would expect, instead it is blank:

Using quarkus-smallrye-openapi and quarkus-resteasy-jackson.

Expected behavior

No response

Actual behavior

No response

How to Reproduce?

No response

Output of uname -a or ver

No response

Output of java -version

17.0.2

GraalVM version (if different from Java)

No response

Quarkus version or git rev

Quarkus 2.8.1.Final

Build tool (ie. output of mvnw --version or gradlew --version)

Gradle 7.4.2

Additional information

No response

[quarkus-bot]

/cc @MikeEdgar, @phillip-kruger

[josephearl]

---
openapi: 3.0.3
info:
  title: Family
  description: Family API
  version: 1.0.0
paths:
  /family/one:
    get:
      tags:
      - Family
      responses:
        "200":
          description: Parent
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Parent'
components:
  schemas:
    Child:
      type: object
      properties:
        name:
          type: string
    Parent:
      type: object
      properties:
        firstChild:
          $ref: '#/components/schemas/Child'
        secondChild:
          allOf:
          - $ref: '#/components/schemas/Child'
          - nullable: true

[josephearl]

https://stackoverflow.com/a/48114924/290028

OAI/OpenAPI-Specification#1368

so I think for 3.0 it should be something like

secondChild:
  nullable: true
  allOf:
  - $ref: '#/components/schemas/Child'

[josephearl]

Tested using https://editor.swagger.io with the original and the patched version and both behave the same way and have the same display issue as in Quarkus, so seems it's an in issue in Swagger UI. I'll file something there.

[gsmet]

@josephearl thanks for taking the time to diagnose this thing and keep us updated!

[josephearl]

Raised swagger-api/swagger-ui#7992