Preserve oneOf wrapper's own properties; keep union constructors public

Author: jasperpatterson

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

@@ -2802,23 +2802,31 @@ protected void updateModelForComposedSchema(CodegenModel m, Schema schema, Map<S
                 addImport(composed, refSchema, m, modelName);
 
                 if (allDefinitions != null && refSchema != null) {
-                    if (ModelUtils.hasOneOf(refSchema)) {
-                        // Do not flatten oneOf variant properties into this model.
-                        // addProperties() would recurse into each variant and merge all
-                        // their properties, producing an impossible conjunction. The oneOf
-                        // ref is already tracked via m.interfaces.
-                    } else if (allParents.contains(ref) && supportsMultipleInheritance) {
+                    // When the refSchema is a oneOf wrapper, do not flatten the variant
+                    // properties into this model — that would produce an impossible
+                    // conjunction of all variants' properties. The wrapper's own
+                    // properties/required (shared fields declared on the wrapper itself)
+                    // should still be inherited. The oneOf variants are tracked via
+                    // m.interfaces. Pre-seeding visitedSchemas with the variant schemas
+                    // suppresses recursion into them inside addProperties().
+                    Set<Schema> visited = new HashSet<>();
+                    if (ModelUtils.hasOneOf(refSchema) && refSchema.getOneOf() != null) {
+                        for (Object variant : refSchema.getOneOf()) {
+                            visited.add((Schema) variant);
+                        }
+                    }
+                    if (allParents.contains(ref) && supportsMultipleInheritance) {
                         // multiple inheritance
-                        addProperties(allProperties, allRequired, refSchema, new HashSet<>());
+                        addProperties(allProperties, allRequired, refSchema, visited);
                     } else if (parentName != null && parentName.equals(ref) && supportsInheritance) {
                         // single inheritance
-                        addProperties(allProperties, allRequired, refSchema, new HashSet<>());
+                        addProperties(allProperties, allRequired, refSchema, visited);
                     } else {
                         // composition
                         Map<String, Schema> newProperties = new LinkedHashMap<>();
-                        addProperties(newProperties, required, refSchema, new HashSet<>());
+                        addProperties(newProperties, required, refSchema, new HashSet<>(visited));
                         mergeProperties(properties, newProperties);
-                        addProperties(allProperties, allRequired, refSchema, new HashSet<>());
+                        addProperties(allProperties, allRequired, refSchema, visited);
                     }
                 }
 

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractCSharpCodegen.java

@@ -707,6 +707,13 @@ private boolean modelIsMutable(CodegenModel model, Set<String> processed) {
             processed = new HashSet<String>();
         }
         boolean isMutable = model.allVars.stream().anyMatch(v -> !v.isReadOnly);
+        // oneOf/anyOf union wrappers expose a constructor per variant; the variants
+        // are not tracked in allVars, so fall back to the composed schema lists.
+        if (!isMutable && model.getComposedSchemas() != null) {
+            List<CodegenProperty> oneOf = model.getComposedSchemas().getOneOf();
+            List<CodegenProperty> anyOf = model.getComposedSchemas().getAnyOf();
+            isMutable = (oneOf != null && !oneOf.isEmpty()) || (anyOf != null && !anyOf.isEmpty());
+        }
         if (!isMutable && !processed.contains(model.classname) && model.getDiscriminator() != null && model.getDiscriminator().getMappedModels() != null) {
             processed.add(model.classname);
             isMutable = modelIsMutable(model, processed);

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

@@ -1216,6 +1216,34 @@ public void testAllOfWithOneOfRefNoDiscriminatorNoInheritance() {
         assertFalse(varNames.contains("zOnlyField"), "vars should not contain variant-specific 'zOnlyField'");
     }
 
+    @Test
+    public void testAllOfWithOneOfRefPreservesWrapperProperties() {
+        final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_0/allOf_oneOf_noDiscriminator.yaml");
+        DefaultCodegen codegen = new DefaultCodegen();
+        codegen.supportsInheritance = true;
+        codegen.setOpenAPI(openAPI);
+
+        // ChildWithSharedFields is a oneOf wrapper that also declares its own
+        // properties (wrapperOptionalField, wrapperRequiredField). When ParentWithSharedFields
+        // inherits from it via allOf, those wrapper-level properties must still flow
+        // through to allProperties/allRequired — only the variant-specific properties
+        // should be suppressed.
+        Schema parentSchema = openAPI.getComponents().getSchemas().get("ParentWithSharedFields");
+        CodegenModel parentModel = codegen.fromModel("ParentWithSharedFields", parentSchema);
+
+        List<String> allVarNames = parentModel.allVars.stream().map(v -> v.name).collect(Collectors.toList());
+        assertTrue(allVarNames.contains("wrapperOptionalField"), "allVars should contain wrapper-level 'wrapperOptionalField'");
+        assertTrue(allVarNames.contains("wrapperRequiredField"), "allVars should contain wrapper-level 'wrapperRequiredField'");
+        assertTrue(allVarNames.contains("extraField"), "allVars should contain inline allOf 'extraField'");
+        assertFalse(allVarNames.contains("xOnlyField"), "allVars should not contain variant-specific 'xOnlyField'");
+        assertFalse(allVarNames.contains("yOnlyField"), "allVars should not contain variant-specific 'yOnlyField'");
+        assertFalse(allVarNames.contains("zOnlyField"), "allVars should not contain variant-specific 'zOnlyField'");
+
+        List<String> requiredVarNames = parentModel.requiredVars.stream().map(v -> v.name).collect(Collectors.toList());
+        assertTrue(requiredVarNames.contains("wrapperRequiredField"), "requiredVars should include wrapper-level required 'wrapperRequiredField'");
+        assertTrue(requiredVarNames.contains("extraField"), "requiredVars should include inline allOf required 'extraField'");
+    }
+
     @Test
     public void testAllOfSingleAndDoubleRefWithOwnPropsNoDiscriminator() {
         final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_0/allOf_composition.yaml");

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

@@ -12,6 +12,15 @@ paths:
             application/json:
               schema:
                 $ref: '#/components/schemas/ParentC'
+  /parent-shared:
+    get:
+      responses:
+        '200':
+          description: OK
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ParentWithSharedFields'
 components:
   schemas:
     ParentC:
@@ -29,6 +38,28 @@ components:
         - $ref: "#/components/schemas/ChildY"
         - $ref: "#/components/schemas/ChildZ"
 
+    ParentWithSharedFields:
+      allOf:
+        - $ref: "#/components/schemas/ChildWithSharedFields"
+        - type: object
+          required: [extraField]
+          properties:
+            extraField:
+              type: string
+
+    ChildWithSharedFields:
+      type: object
+      required: [wrapperRequiredField]
+      properties:
+        wrapperOptionalField:
+          type: string
+        wrapperRequiredField:
+          type: string
+      oneOf:
+        - $ref: "#/components/schemas/ChildX"
+        - $ref: "#/components/schemas/ChildY"
+        - $ref: "#/components/schemas/ChildZ"
+
     ChildX:
       type: object
       required: [kind, sharedField, xOnlyField]

samples/client/petstore/csharp/generichost/latest/UseDateTimeOffset/src/Org.OpenAPITools/Model/NullableShape.cs

@@ -34,7 +34,7 @@ public partial class NullableShape : IValidatableObject
         /// Initializes a new instance of the <see cref="NullableShape" /> class.
         /// </summary>
         /// <param name="triangle"></param>
-        internal NullableShape(Triangle triangle)
+        public NullableShape(Triangle triangle)
         {
             Triangle = triangle;
             OnCreated();
@@ -44,7 +44,7 @@ internal NullableShape(Triangle triangle)
         /// Initializes a new instance of the <see cref="NullableShape" /> class.
         /// </summary>
         /// <param name="quadrilateral"></param>
-        internal NullableShape(Quadrilateral quadrilateral)
+        public NullableShape(Quadrilateral quadrilateral)
         {
             Quadrilateral = quadrilateral;
             OnCreated();

samples/client/petstore/csharp/generichost/latest/UseDateTimeOffset/src/Org.OpenAPITools/Model/OneOfString.cs

@@ -34,7 +34,7 @@ public partial class OneOfString : IValidatableObject
         /// Initializes a new instance of the <see cref="OneOfString" /> class.
         /// </summary>
         /// <param name="string"></param>
-        internal OneOfString(string @string)
+        public OneOfString(string @string)
         {
             String = @string;
             OnCreated();

samples/client/petstore/csharp/generichost/latest/UseDateTimeOffset/src/Org.OpenAPITools/Model/PolymorphicProperty.cs

@@ -34,7 +34,7 @@ public partial class PolymorphicProperty : IValidatableObject
         /// Initializes a new instance of the <see cref="PolymorphicProperty" /> class.
         /// </summary>
         /// <param name="bool"></param>
-        internal PolymorphicProperty(bool @bool)
+        public PolymorphicProperty(bool @bool)
         {
             Bool = @bool;
             OnCreated();
@@ -44,7 +44,7 @@ internal PolymorphicProperty(bool @bool)
         /// Initializes a new instance of the <see cref="PolymorphicProperty" /> class.
         /// </summary>
         /// <param name="string"></param>
-        internal PolymorphicProperty(string @string)
+        public PolymorphicProperty(string @string)
         {
             String = @string;
             OnCreated();
@@ -54,7 +54,7 @@ internal PolymorphicProperty(string @string)
         /// Initializes a new instance of the <see cref="PolymorphicProperty" /> class.
         /// </summary>
         /// <param name="object"></param>
-        internal PolymorphicProperty(Object @object)
+        public PolymorphicProperty(Object @object)
         {
             Object = @object;
             OnCreated();
@@ -64,7 +64,7 @@ internal PolymorphicProperty(Object @object)
         /// Initializes a new instance of the <see cref="PolymorphicProperty" /> class.
         /// </summary>
         /// <param name="list"></param>
-        internal PolymorphicProperty(List<string> list)
+        public PolymorphicProperty(List<string> list)
         {
             List = list;
             OnCreated();

samples/client/petstore/csharp/generichost/latest/UseDateTimeOffset/src/Org.OpenAPITools/Model/Shape.cs

@@ -34,7 +34,7 @@ public partial class Shape : IValidatableObject
         /// Initializes a new instance of the <see cref="Shape" /> class.
         /// </summary>
         /// <param name="triangle"></param>
-        internal Shape(Triangle triangle)
+        public Shape(Triangle triangle)
         {
             Triangle = triangle;
             OnCreated();
@@ -44,7 +44,7 @@ internal Shape(Triangle triangle)
         /// Initializes a new instance of the <see cref="Shape" /> class.
         /// </summary>
         /// <param name="quadrilateral"></param>
-        internal Shape(Quadrilateral quadrilateral)
+        public Shape(Quadrilateral quadrilateral)
         {
             Quadrilateral = quadrilateral;
             OnCreated();

samples/client/petstore/csharp/generichost/latest/UseDateTimeOffset/src/Org.OpenAPITools/Model/ShapeOrNull.cs

@@ -34,7 +34,7 @@ public partial class ShapeOrNull : IValidatableObject
         /// Initializes a new instance of the <see cref="ShapeOrNull" /> class.
         /// </summary>
         /// <param name="triangle"></param>
-        internal ShapeOrNull(Triangle triangle)
+        public ShapeOrNull(Triangle triangle)
         {
             Triangle = triangle;
             OnCreated();
@@ -44,7 +44,7 @@ internal ShapeOrNull(Triangle triangle)
         /// Initializes a new instance of the <see cref="ShapeOrNull" /> class.
         /// </summary>
         /// <param name="quadrilateral"></param>
-        internal ShapeOrNull(Quadrilateral quadrilateral)
+        public ShapeOrNull(Quadrilateral quadrilateral)
         {
             Quadrilateral = quadrilateral;
             OnCreated();

samples/client/petstore/csharp/generichost/net10/FormModels/src/Org.OpenAPITools/Model/NullableShape.cs

@@ -33,7 +33,7 @@ public partial class NullableShape : IValidatableObject
         /// Initializes a new instance of the <see cref="NullableShape" /> class.
         /// </summary>
         /// <param name="triangle"></param>
-        internal NullableShape(Triangle triangle)
+        public NullableShape(Triangle triangle)
         {
             Triangle = triangle;
             OnCreated();
@@ -43,7 +43,7 @@ internal NullableShape(Triangle triangle)
         /// Initializes a new instance of the <see cref="NullableShape" /> class.
         /// </summary>
         /// <param name="quadrilateral"></param>
-        internal NullableShape(Quadrilateral quadrilateral)
+        public NullableShape(Quadrilateral quadrilateral)
         {
             Quadrilateral = quadrilateral;
             OnCreated();