Fix ClassCastException when allOf array changes to type array

core/src/main/java/org/openapitools/openapidiff/core/compare/SchemaDiff.java

@@ -240,6 +240,9 @@ protected static <T, U> Schema<T> addSchema(Schema<T> schema, Schema<U> fromSche
     if (fromSchema.getMinItems() != null) {
       schema.setMinItems(fromSchema.getMinItems());
     }
+    if (fromSchema.getItems() != null) {
+      schema.setItems(fromSchema.getItems());
+    }
     if (fromSchema.getMaxProperties() != null) {
       schema.setMaxProperties(fromSchema.getMaxProperties());
     }

core/src/main/java/org/openapitools/openapidiff/core/compare/schemadiffresult/ArraySchemaDiffResult.java

@@ -1,7 +1,6 @@
 package org.openapitools.openapidiff.core.compare.schemadiffresult;
 
 import io.swagger.v3.oas.models.Components;
-import io.swagger.v3.oas.models.media.ArraySchema;
 import io.swagger.v3.oas.models.media.Schema;
 import org.openapitools.openapidiff.core.compare.OpenApiDiff;
 import org.openapitools.openapidiff.core.model.ChangedSchema;
@@ -22,9 +21,6 @@ public <T extends Schema<X>, X> DeferredChanged<ChangedSchema> diff(
       T left,
       T right,
       DiffContext context) {
-    ArraySchema leftArraySchema = (ArraySchema) left;
-    ArraySchema rightArraySchema = (ArraySchema) right;
-
     DeferredChanged<ChangedSchema> superSchemaDiff =
         super.diff(refSet, leftComponents, rightComponents, left, right, context)
             .flatMap(
@@ -34,8 +30,8 @@ public <T extends Schema<X>, X> DeferredChanged<ChangedSchema> diff(
                           .getSchemaDiff()
                           .diff(
                               refSet,
-                              leftArraySchema.getItems(),
-                              rightArraySchema.getItems(),
+                              left.getItems(),
+                              right.getItems(),
                               context.copyWithRequired(true));
                   itemsDiff.ifPresent(changedSchema::setItems);
                   return itemsDiff;

core/src/test/java/org/openapitools/openapidiff/core/Issue887Test.java

@@ -0,0 +1,29 @@
+package org.openapitools.openapidiff.core;
+
+import static org.assertj.core.api.Assertions.assertThatCode;
+import static org.openapitools.openapidiff.core.TestUtils.assertOpenApiAreEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class Issue887Test {
+
+  private final String ALLOF_ARRAY = "issue-887-1.yaml";
+  private final String DIRECT_ARRAY = "issue-887-2.yaml";
+
+  @Test
+  public void testAllOfArrayToDirectArrayDoesNotThrow() {
+    assertThatCode(() -> OpenApiCompare.fromLocations(ALLOF_ARRAY, DIRECT_ARRAY))
+        .doesNotThrowAnyException();
+  }
+
+  @Test
+  public void testDirectArrayToAllOfArrayDoesNotThrow() {
+    assertThatCode(() -> OpenApiCompare.fromLocations(DIRECT_ARRAY, ALLOF_ARRAY))
+        .doesNotThrowAnyException();
+  }
+
+  @Test
+  public void testAllOfArrayToDirectArrayAreEquals() {
+    assertOpenApiAreEquals(ALLOF_ARRAY, DIRECT_ARRAY);
+  }
+}

core/src/test/resources/issue-887-1.yaml

@@ -0,0 +1,32 @@
+openapi: 3.0.3
+info:
+  title: Test API
+  version: 1.0.0
+
+paths:
+  /test:
+    get:
+      responses:
+        '200':
+          description: OK
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/TestResponse'
+
+components:
+  schemas:
+    TestResponse:
+      type: object
+      properties:
+        valuations:
+          allOf:
+            - $ref: '#/components/schemas/Valuations'
+
+    Valuations:
+      type: array
+      items:
+        type: object
+        properties:
+          value:
+            type: string

core/src/test/resources/issue-887-2.yaml

@@ -0,0 +1,31 @@
+openapi: 3.0.3
+info:
+  title: Test API
+  version: 1.0.0
+
+paths:
+  /test:
+    get:
+      responses:
+        '200':
+          description: OK
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/TestResponse'
+
+components:
+  schemas:
+    TestResponse:
+      type: object
+      properties:
+        valuations:
+          type: array
+          items:
+            $ref: '#/components/schemas/Valuation'
+
+    Valuation:
+      type: object
+      properties:
+        value:
+          type: string