address PR feedback

Author: eric-driggs

modules/openapi-generator/src/main/java/org/openapitools/codegen/utils/ModelUtils.java

@@ -2363,11 +2363,12 @@ public static boolean isNullTypeSchema(OpenAPI openAPI, Schema schema) {
             return false;
         }
 
-        // OpenAPI 3.0.x: empty nullable object is a null-type schema
+        // OpenAPI 3.0.x: nullable object with no properties or constraints expresses nullability
         if (!(schema instanceof JsonSchema) // 3.0.x only
                 && "object".equals(schema.getType())
                 && Boolean.TRUE.equals(schema.getNullable())
-                && schema.get$ref() == null) {
+                && schema.get$ref() == null
+                && schema.getAdditionalProperties() == null) {
             return true;
         }
 

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

@@ -4327,9 +4327,9 @@ public void testJspecify(String library, boolean useSpringBoot4, boolean hasJspe
     }
 
     @Test(description = "anyOf with $ref and {type: object, nullable: true} should resolve to typed nullable field, not Object")
-    public void testAnyOfNullableObjectSentinelResolvesToTypedField() {
+    public void testAnyOfBareNullableObjectResolvesToTypedField() {
         Map<String, File> files = generateFromContract(
-                "src/test/resources/bugs/issue_anyof_nullable_object_sentinel.yaml",
+                "src/test/resources/bugs/issue_anyof_bare_nullable_object.yaml",
                 JavaClientCodegen.JERSEY3);
 
         JavaFileAssert.assertThat(files.get("Order.java"))

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

@@ -655,19 +655,23 @@ public void isNullTypeSchemaTest() {
         schema = openAPI.getComponents().getSchemas().get("JustDescription");
         assertFalse(ModelUtils.isNullTypeSchema(openAPI, schema));
 
-        // {type: "object", nullable: true} with no properties is a null sentinel (apispec 6.7.1+)
-        schema = openAPI.getComponents().getSchemas().get("NullableObjectSentinel");
+        // {type: "object", nullable: true} with no properties/constraints expresses nullability (OAS 3.0.3)
+        schema = openAPI.getComponents().getSchemas().get("BareNullableObject");
         assertTrue(ModelUtils.isNullTypeSchema(openAPI, schema));
 
-        // {type: "object", nullable: true} WITH properties is a real object, not a null sentinel
+        // {type: "object", nullable: true} WITH properties is a real object, not expressing nullability
         schema = openAPI.getComponents().getSchemas().get("NullableObjectWithProperties");
         assertFalse(ModelUtils.isNullTypeSchema(openAPI, schema));
+
+        // {type: "object", nullable: true, additionalProperties: ...} is a nullable map, not expressing nullability
+        schema = openAPI.getComponents().getSchemas().get("NullableObjectMap");
+        assertFalse(ModelUtils.isNullTypeSchema(openAPI, schema));
     }
 
     @Test
-    public void isNullTypeSchemaInlineAnyOfSentinelTest() {
+    public void isNullTypeSchemaTestBareNullableObject() {
         OpenAPI openAPI = TestUtils.parseSpec(
-                "src/test/resources/bugs/issue_anyof_nullable_object_sentinel.yaml");
+                "src/test/resources/bugs/issue_anyof_bare_nullable_object.yaml");
         Schema order = (Schema) openAPI.getComponents().getSchemas().get("Order");
         Schema shippingProp = (Schema) order.getProperties().get("shippingAddress");
         assertNotNull(shippingProp.getAnyOf(), "shippingAddress should have anyOf");
@@ -679,10 +683,10 @@ public void isNullTypeSchemaInlineAnyOfSentinelTest() {
         Schema refSchema = anyOf.get(0);
         assertFalse(ModelUtils.isNullTypeSchema(openAPI, refSchema));
 
-        // second sub-schema is {type: object, nullable: true} — the sentinel
-        Schema sentinel = anyOf.get(1);
-        assertTrue(ModelUtils.isNullTypeSchema(openAPI, sentinel),
-                "Should recognize {type: object, nullable: true} as null sentinel");
+        // second sub-schema is {type: object, nullable: true} — expresses nullability
+        Schema bareNullableObject = anyOf.get(1);
+        assertTrue(ModelUtils.isNullTypeSchema(openAPI, bareNullableObject),
+                "{type: object, nullable: true} with no properties/constraints expresses nullability");
     }
 
     @Test
@@ -725,9 +729,9 @@ public void isNullTypeSchemaTestWith31Spec() {
         schema = openAPI.getComponents().getSchemas().get("JustDescription");
         assertFalse(ModelUtils.isNullTypeSchema(openAPI, schema));
 
-        // In 3.1, {type: object, nullable: true} is NOT a null sentinel — it's a real
+        // In 3.1, {type: object, nullable: true} is NOT a null type — it's a real
         // nullable object. Nullability in 3.1 is expressed via type: ["object", "null"].
-        schema = openAPI.getComponents().getSchemas().get("NullableObjectSentinel");
+        schema = openAPI.getComponents().getSchemas().get("BareNullableObject");
         assertFalse(ModelUtils.isNullTypeSchema(openAPI, schema));
     }
 

modules/openapi-generator/src/test/resources/3_0/null_schema_test.yaml

@@ -105,12 +105,17 @@ components:
         - $ref: '#/components/schemas/StringRef'
     JustDescription:
       description: A schema with just description
-    NullableObjectSentinel:
+    BareNullableObject:
       type: object
       nullable: true
     NullableObjectWithProperties:
       type: object
       nullable: true
       properties:
         name:
-          type: string
+          type: string
+    NullableObjectMap:
+      type: object
+      nullable: true
+      additionalProperties:
+        type: string

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

@@ -105,6 +105,6 @@ components:
         - $ref: '#/components/schemas/StringRef'
     JustDescription:
       description: A schema with just description
-    NullableObjectSentinel:
+    BareNullableObject:
       type: object
       nullable: true

…ssue_anyof_nullable_object_sentinel.yaml …gs/issue_anyof_bare_nullable_object.yamlmodules/openapi-generator/src/test/resources/bugs/issue_anyof_nullable_object_sentinel.yaml renamed to modules/openapi-generator/src/test/resources/bugs/issue_anyof_bare_nullable_object.yaml modules/openapi-generator/src/test/resources/bugs/issue_anyof_nullable_object_sentinel.yaml renamed to modules/openapi-generator/src/test/resources/bugs/issue_anyof_bare_nullable_object.yaml

@@ -1,6 +1,6 @@
 openapi: 3.0.3
 info:
-  title: anyOf nullable object sentinel test
+  title: anyOf bare nullable object test
   description: >
     Tests that anyOf with a $ref and {type: object, nullable: true} (no properties)
     is simplified to a typed nullable field, not Object.