[Bug] Backward compatibility check fails on reordered discriminator mappings

Ran into a compatibility issue, which I believe is a false positive. I have one polymorphic schema, that maps to two different property names. The backwards compatibility check fails if the mappings are re-ordered.

This should not be failing, because neither discriminator names nor the mapping changed.

For example, the following 2 should be considered compatible, but are not. Assume the actual schemas are identical. Schema A is mapped to a-type and z-type which are present in both mappings, but are ordered differently.

             schema:
               oneOf:
                 - $ref: '#/components/schemas/A'
                 - $ref: '#/components/schemas/B'
               discriminator:
                 propertyName: realtype
                 mapping:
                   z-type: '#/components/schemas/A'
                   a-type: '#/components/schemas/A'
                   b-type: '#/components/schemas/B'

and

              schema:
                oneOf:
                  - $ref: '#/components/schemas/A'
                  - $ref: '#/components/schemas/B'
                discriminator:
                  propertyName: realtype
                  mapping:
                    a-type: '#/components/schemas/A'
                    z-type: '#/components/schemas/A'
                    b-type: '#/components/schemas/B'

I was able to reproduce this in this repo by adding a test to OneOfDiffTest with the above as an example (based on oneOf_discriminator-missing_1.yaml).

  @Test
  public void testOneOfDiscrimitatorDifferentOrder() {
    assertOpenApiAreEquals(OPENAPI_DOC11, OPENAPI_DOC12);
  }

既存の OneOfDiffTest と、issue で言及されている oneOf_discriminator-missing_1.yaml の例から始めます。マッピングを並べ替えたケースを追加または実行し、そのケースが通る比較のエントリポイントを追跡します。2 つの示されたスキーマが、discriminator マッピングの順序だけが異なる場合に互換として扱われれば完了です。