Stackoverflow error with cyclic references involving allOf

Given this schema definition

openapi: 3.0.1
info:
  title: recursive test
  version: '1.0'
servers:
  - url: 'http://localhost:8000/'
paths:
  /ping:
    get:
      operationId: ping
      responses:
        '200':
          description: OK
          content:
            text/plain:
              schema:
                $ref: '#/components/schemas/B'
components:
  schemas:
    B:
      type: object
      properties:
        message:
          type: string
        message2:
          type: string
        details:
          type: array
          items:
            allOf:
              - $ref: '#/components/schemas/B'

and running openapi-diff spec.yaml spec.yaml I get stack overflow error

Exception in thread "main" java.lang.StackOverflowError
        at java.base/java.util.Arrays.spliterator(Arrays.java:5482)
        at java.base/java.util.Arrays.stream(Arrays.java:5633)
        at java.base/java.util.Arrays.stream(Arrays.java:5614)
        at java.base/java.util.stream.Stream.of(Stream.java:1188)
        at com.qdesrame.openapi.diff.model.ChangedExtensions.getChangedElements(ChangedExtensions.java:37)
        at com.qdesrame.openapi.diff.model.ComposedChanged.isChanged(ComposedChanged.java:19)
        at com.qdesrame.openapi.diff.model.Changed.isUnchanged(Changed.java:21)
        at com.qdesrame.openapi.diff.utils.ChangedUtils.isUnchanged(ChangedUtils.java:9)
        at com.qdesrame.openapi.diff.utils.ChangedUtils.isChanged(ChangedUtils.java:17)
        at com.qdesrame.openapi.diff.compare.ExtensionsDiff.diff(ExtensionsDiff.java:79)
        at com.qdesrame.openapi.diff.compare.schemadiffresult.SchemaDiffResult.diff(SchemaDiffResult.java:61)
        at com.qdesrame.openapi.diff.compare.SchemaDiff.computeDiff(SchemaDiff.java:316)
        at com.qdesrame.openapi.diff.compare.SchemaDiff.computeDiff(SchemaDiff.java:27)
        at com.qdesrame.openapi.diff.compare.ReferenceDiffCache.cachedDiff(ReferenceDiffCache.java:51)
        at com.qdesrame.openapi.diff.compare.SchemaDiff.diff(SchemaDiff.java:282)
        at com.qdesrame.openapi.diff.compare.schemadiffresult.SchemaDiffResult.diff(SchemaDiffResult.java:75)
        at com.qdesrame.openapi.diff.compare.schemadiffresult.ComposedSchemaDiffResult.diff(ComposedSchemaDiffResult.java:85)
        at com.qdesrame.openapi.diff.compare.SchemaDiff.computeDiff(SchemaDiff.java:316)
        at com.qdesrame.openapi.diff.compare.SchemaDiff.computeDiff(SchemaDiff.java:27)
        at com.qdesrame.openapi.diff.compare.ReferenceDiffCache.cachedDiff(ReferenceDiffCache.java:51)
        at com.qdesrame.openapi.diff.compare.SchemaDiff.diff(SchemaDiff.java:282)
        at com.qdesrame.openapi.diff.compare.schemadiffresult.ArraySchemaDiffResult.diff(ArraySchemaDiffResult.java:31)

The problem occurs only with allOf. Replacing it with oneOf fixes the problem.

提供されたスキーマと openapi-diff spec.yaml spec.yaml を使って失敗を再現します。スタックトレースを入口として、SchemaDiff、ReferenceDiffCache、ComposedSchemaDiffResult、ArraySchemaDiffResult を通る再帰呼び出しを追跡します。再帰的な allOf スキーマ比較が StackOverflowError なしで完了すれば完了です。