Issue 21890: added test (first draft)

Author: Marco

modules/openapi-generator/src/test/java/org/openapitools/codegen/java/AbstractJavaCodegenTest.java

@@ -25,10 +25,7 @@
 import io.swagger.v3.parser.core.models.ParseOptions;
 import org.mockito.Answers;
 import org.mockito.Mockito;
-import org.openapitools.codegen.CodegenConstants;
-import org.openapitools.codegen.CodegenModel;
-import org.openapitools.codegen.CodegenParameter;
-import org.openapitools.codegen.TestUtils;
+import org.openapitools.codegen.*;
 import org.openapitools.codegen.languages.AbstractJavaCodegen;
 import org.openapitools.codegen.testutils.ConfigAssert;
 import org.openapitools.codegen.utils.ModelUtils;
@@ -755,6 +752,20 @@ public void nullDefaultValueForModelWithDynamicProperties() {
         Assert.assertEquals(defaultValue, "null");
     }
 
+    @Test
+    public void defaultEmptyListForModelWithAdditionalPropertyDefaultToEmptyContainer() {
+        final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_1/java/issue_21890.yaml");
+        codegen.additionalProperties().put(CodegenConstants.DEFAULT_TO_EMPTY_CONTAINER, "map");
+        codegen.processOpts();
+        codegen.setOpenAPI(openAPI);
+
+        Schema<?> schema = openAPI.getComponents().getSchemas().get("Pet_parents");
+
+        CodegenProperty parents = codegen.fromProperty("parents", schema, true);
+        String defaultValue = codegen.toDefaultValue(parents, schema);
+        Assert.assertEquals(defaultValue, "new HashMap()");
+    }
+
     @Test
     public void maplikeDefaultValueForModelWithStringToStringMapping() {
         final OpenAPI openAPI = FLATTENED_SPEC.get("3_0/mapSchemas");

modules/openapi-generator/src/test/resources/3_1/java/issue_21890.yaml

@@ -0,0 +1,57 @@
+openapi: 3.1.0
+servers:
+  - url: 'http://petstore.swagger.io/v2'
+info:
+  description: >-
+    This is a sample server Petstore server. For this sample, you can use the api key
+    `special-key` to test the authorization filters.
+  version: 1.0.0
+  title: OpenAPI Petstore
+  license:
+    name: Apache-2.0
+    url: 'https://www.apache.org/licenses/LICENSE-2.0.html'
+paths:
+  '/pet/{petId}':
+    get:
+      tags:
+        - pet
+      summary: Find pet by ID
+      description: Returns a single pet
+      operationId: getPetById
+      parameters:
+        - name: petId
+          in: path
+          description: ID of pet to return
+          required: true
+          schema:
+            type: integer
+            format: int64
+      responses:
+        '200':
+          description: successful operation
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Pet'
+        '400':
+          description: Invalid ID supplied
+        '404':
+          description: Pet not found
+components:
+  schemas:
+    Pet:
+      title: a Pet
+      description: A pet for sale in the pet store
+      type: object
+      properties:
+        parents:
+          type: object
+          properties:
+            mother:
+              type: string
+            father:
+              type: string
+      required:
+        - parents
+
+