[BUG] [ExampleGenerator] Generated examples from nested composed schema types are missing (allOf of allOf)

[phpinhei-te]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

Nested composed schemas are missing generated examples for child schema types, only the parent schema examples get generated while child examples are ignored.

openapi-generator version

v7.5.0 and master 93f4323

OpenAPI declaration file content or url

While generating examples for ExampleAllOfParentSchema schema:

components:
  schemas:
    ExampleSchema:
      type: object
      properties:
        example_schema_property:
          type: string
          example: example schema property value
    ExampleAllOfSchema:
      type: object
      allOf:
        - $ref: '#/components/schemas/ExampleSchema'
        - type: object
          properties:
            example_schema_property_composed:
              type: string
              example: example schema property value composed
    ExampleAllOfParentSchema:
      type: object
      allOf:
        - $ref: '#/components/schemas/ExampleAllOfSchema'
        - type: object
          properties:
            example_schema_property_composed_parent:
              type: string
              example: example schema property value composed parent

It is expected to have the following generated example:

{
  "example_schema_property_composed_parent" : "example schema property value composed parent",
  "example_schema_property_composed" : "example schema property value composed",
  "example_schema_property" : "example schema property value"
}

However, ExampleGenerator provides the following:

{
  "example_schema_property_composed_parent" : "example schema property value composed parent"
}

Generation Details

N/A

Steps to reproduce

Added new example to example_generator_test.yaml:

Index: modules/openapi-generator/src/test/resources/3_0/example_generator_test.yaml
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/modules/openapi-generator/src/test/resources/3_0/example_generator_test.yaml b/modules/openapi-generator/src/test/resources/3_0/example_generator_test.yaml
--- a/modules/openapi-generator/src/test/resources/3_0/example_generator_test.yaml	(revision 93f43233645bdb57a0f57417955069b5a3dd6ae1)
+++ b/modules/openapi-generator/src/test/resources/3_0/example_generator_test.yaml	(date 1713610291806)
@@ -81,6 +81,21 @@
             application/json:
               schema:
                 $ref: '#/components/schemas/ExampleAllOfSchema'
+  /generate_from_response_schema_with_array_of_allOf_composed_model:
+    get:
+      operationId: generateFromResponseSchemaWithAllOfModel
+      responses:
+        '200':
+          description: successful operation
+          content:
+            application/json:
+              schema:
+#                type: object
+#                properties:
+#                  schemas:
+#                type: array
+#                items:
+                $ref: '#/components/schemas/ExampleAllOfParentSchema'
   /generate_from_response_schema_with_anyOf_composed_model:
     get:
       operationId: generateFromResponseSchemaWithAnyOfModel
@@ -131,6 +146,15 @@
             example_schema_property_composed:
               type: string
               example: example schema property value composed
+    ExampleAllOfParentSchema:
+      type: object
+      allOf:
+        - $ref: '#/components/schemas/ExampleAllOfSchema'
+        - type: object
+          properties:
+            example_schema_property_composed_parent:
+              type: string
+              example: example schema property value composed parent
     ExampleAnyOfSchema:
       type: object
       anyOf:

Included unit test to ExampleGeneratorTest.java to test scenario:

Index: modules/openapi-generator/src/test/java/org/openapitools/codegen/ExampleGeneratorTest.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/ExampleGeneratorTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/ExampleGeneratorTest.java
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/ExampleGeneratorTest.java	(revision 93f43233645bdb57a0f57417955069b5a3dd6ae1)
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/ExampleGeneratorTest.java	(date 1713612240848)
@@ -210,6 +210,39 @@
         assertEquals("200", examples.get(0).get("statusCode"));
     }
 
+    @Test
+    public void generateFromResponseSchemaWithArrayAllOfComposedModel() {
+        OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_0/example_generator_test.yaml");
+
+        new InlineModelResolver().flatten(openAPI);
+
+        ExampleGenerator exampleGenerator = new ExampleGenerator(openAPI.getComponents().getSchemas(), openAPI);
+        Set<String> mediaTypeKeys = new TreeSet<>();
+        mediaTypeKeys.add("application/json");
+        List<Map<String, String>> examples = exampleGenerator.generateFromResponseSchema(
+                "200",
+                openAPI
+                        .getPaths()
+                        .get("/generate_from_response_schema_with_array_of_allOf_composed_model")
+                        .getGet()
+                        .getResponses()
+                        .get("200")
+                        .getContent()
+                        .get("application/json")
+                        .getSchema(),
+                mediaTypeKeys
+        );
+
+        assertEquals(1, examples.size());
+        assertEquals("application/json", examples.get(0).get("contentType"));
+        assertEquals(String.format(Locale.ROOT, "{\n" +
+                                                "  \"example_schema_property_composed_parent\" : \"example schema property value composed parent\",\n" +
+                                                "  \"example_schema_property_composed\" : \"example schema property value composed\",\n" +
+                                                "  \"example_schema_property\" : \"example schema property value\"\n" +
+                                                "}"), examples.get(0).get("example"));
+        assertEquals("200", examples.get(0).get("statusCode"));
+    }
+
     @Test
     public void generateFromResponseSchemaWithOneOfComposedModel() {
         OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_0/example_generator_test.yaml");

Related issues/PRs

Simular to this:
#17497
Seems like an edge case from the added implementation

Suggest a fix

Didn't go into detail yet, but most likely ExampleGenerator:373 needs to consider the resolved schema to have allOf/anyOf/oneOf:

        } else if (ModelUtils.isAllOf(schema) || ModelUtils.isAllOfWithProperties(schema)) {
            LOGGER.debug("Resolving allOf model '{}' to example", name);
            List<Schema> interfaces = schema.getAllOf();
            for (Schema composed : interfaces) {
                traverseSchemaProperties(mediaType, composed, processedModels, values);
                if (composed.get$ref() != null) {
                    String ref = ModelUtils.getSimpleRef(composed.get$ref());
                    Schema resolved = ModelUtils.getSchema(openAPI, ref);
                    if (resolved != null) {
                        traverseSchemaProperties(mediaType, resolved, processedModels, values);
                    }
                }
            }
            schema.setExample(values);
            return schema.getExample();
        }

If I have sometime during the week I will try to solve it myself.