[Bug]: Loss the xml entry for enum, union

[skywing918]

Describe the bug

Playground

the EnumStatus and UnionData has no xml property.

Reproduction

openapi: 3.0.0
info:
  title: (title)
  version: 0.0.0
tags: []
paths: {}
components:
  schemas:
    Book:
      type: object
      required:
        - status
        - unions
      properties:
        status:
          allOf:
            - $ref: '#/components/schemas/EnumStatus'
          xml:
            name: status
        unions:
          type: array
          items:
            allOf:
              - $ref: '#/components/schemas/UnionData'
            xml:
              name: XmlUnionData  # ---> not sure if expect.
          xml:
            wrapped: true
    EnumStatus:
      type: string
      enum:
        - Active
        - Inactive
       xml:
           name: XmlEnumStatus     # ---> expected
    UnionData:
      type: string
      enum:
        - Active
        - Inactive
       xml:
           name: XmlUnionData     # ---> expected

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