fix: set isOverridden from the model's own properties rather than only when unset

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

@@ -6331,8 +6331,12 @@ protected void addVars(IJsonSchemaValidationProperties m, List<CodegenProperty>
                     cp = fromProperty(key, prop, mandatory.contains(key));
                 }
 
-                if (cm != null && cm.allVars == vars && cp.isOverridden == null) { // processing allVars and it's a parent property
-                    cp.isOverridden = true;
+                if (cm != null && cm.allVars == vars) {
+                    // Processing allVars: a property is overridden when it comes from the parent rather than
+                    // being declared by this model. fromProperty caches CodegenProperty instances, so the flag
+                    // must be assigned rather than only filled in when unset - a cached instance may already
+                    // carry a value from whichever model happened to be processed first.
+                    cp.isOverridden = !varsMap.containsKey(key);
                 }
 
                 vars.add(cp);

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

@@ -2362,6 +2362,23 @@ public void testIsOverriddenProperty() {
         Assertions.assertEquals(cp1.isOverridden, false);
     }
 
+    @Test
+    public void testOverrideSetterWhenChildIsDeclaredBeforeParent() {
+        final Path output = newTempFolder();
+        OpenAPI openAPI = new OpenAPIParser()
+                .readLocation("src/test/resources/3_0/allOf_composition_discriminator_child_first.yaml", null, null)
+                .getOpenAPI();
+
+        JavaClientCodegen codegen = new JavaClientCodegen();
+        codegen.setOutputDir(output.toString());
+        codegen.setLibrary(JavaClientCodegen.APACHE);
+
+        new DefaultGenerator().opts(new ClientOptInput().openAPI(openAPI).config(codegen)).generate();
+
+        assertThat(output.resolve("src/main/java/org/openapitools/client/model/Cat.java")).content()
+                .contains("  @Override\n  public Cat petType(@javax.annotation.Nonnull String petType) {");
+    }
+
     @Test
     public void testForJavaApacheHttpClientOverrideSetter() {
         final Path output = newTempFolder();

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

@@ -0,0 +1,52 @@
+openapi: 3.0.2
+info:
+  title: OAI Specification example for Polymorphism
+  version: 1.0.0
+paths:
+  /pet:
+    get:
+      responses:
+        '200':
+          description: desc
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Pet'
+components:
+  schemas:
+    MyPets:
+      oneOf:
+        - $ref: '#/components/schemas/Cat'
+        - $ref: '#/components/schemas/Dog'
+      discriminator:
+        propertyName: petType
+    Pet:
+      type: object
+      required:
+        - petType
+      properties:
+        petType:
+          type: string
+      discriminator:
+        propertyName: petType
+    Cat:
+      allOf:
+        - $ref: '#/components/schemas/Pet'
+        - type: object
+          properties:
+            name:
+              type: string
+            characteristics:
+              $ref: '#/components/schemas/Characteristics'
+    Dog:
+      allOf:
+        - $ref: '#/components/schemas/Pet'
+        - type: object
+          properties:
+            bark:
+              type: string
+    Characteristics:
+      type: object
+      properties:
+        canHunt:
+          type: boolean

samples/client/others/java/restclient-sealedInterface/src/main/java/org/openapitools/client/model/BarRef.java

@@ -79,6 +79,18 @@ public BarRef atType(@jakarta.annotation.Nonnull String atType) {
     return this;
   }
 
+  @Override
+  public BarRef name(@jakarta.annotation.Nullable String name) {
+    this.setName(name);
+    return this;
+  }
+
+  @Override
+  public BarRef atReferredType(@jakarta.annotation.Nullable String atReferredType) {
+    this.setAtReferredType(atReferredType);
+    return this;
+  }
+
   @Override
   public boolean equals(Object o) {
     if (this == o) {

samples/client/others/java/restclient-sealedInterface/src/main/java/org/openapitools/client/model/FooRef.java

@@ -109,6 +109,18 @@ public FooRef atType(@jakarta.annotation.Nonnull String atType) {
     return this;
   }
 
+  @Override
+  public FooRef name(@jakarta.annotation.Nullable String name) {
+    this.setName(name);
+    return this;
+  }
+
+  @Override
+  public FooRef atReferredType(@jakarta.annotation.Nullable String atReferredType) {
+    this.setAtReferredType(atReferredType);
+    return this;
+  }
+
   @Override
   public boolean equals(Object o) {
     if (this == o) {

samples/client/others/java/restclient-sealedInterface/src/main/java/org/openapitools/client/model/PizzaSpeziale.java

@@ -110,6 +110,12 @@ public PizzaSpeziale atType(@jakarta.annotation.Nonnull String atType) {
     return this;
   }
 
+  @Override
+  public PizzaSpeziale pizzaSize(@jakarta.annotation.Nullable BigDecimal pizzaSize) {
+    this.setPizzaSize(pizzaSize);
+    return this;
+  }
+
   @Override
   public boolean equals(Object o) {
     if (this == o) {

samples/client/others/java/webclient-sealedInterface/src/main/java/org/openapitools/client/model/Bar.java

@@ -166,6 +166,30 @@ public void setFoo(@javax.annotation.Nullable FooRefOrValue foo) {
   }
 
 
+  @Override
+  public Bar href(@javax.annotation.Nullable String href) {
+    this.setHref(href);
+    return this;
+  }
+
+  @Override
+  public Bar atSchemaLocation(@javax.annotation.Nullable String atSchemaLocation) {
+    this.setAtSchemaLocation(atSchemaLocation);
+    return this;
+  }
+
+  @Override
+  public Bar atBaseType(@javax.annotation.Nullable String atBaseType) {
+    this.setAtBaseType(atBaseType);
+    return this;
+  }
+
+  @Override
+  public Bar atType(@javax.annotation.Nonnull String atType) {
+    this.setAtType(atType);
+    return this;
+  }
+
   @Override
   public boolean equals(Object o) {
     if (this == o) {

samples/client/others/java/webclient-sealedInterface/src/main/java/org/openapitools/client/model/BarCreate.java

@@ -137,6 +137,36 @@ public void setFoo(@javax.annotation.Nullable FooRefOrValue foo) {
   }
 
 
+  @Override
+  public BarCreate href(@javax.annotation.Nullable String href) {
+    this.setHref(href);
+    return this;
+  }
+
+  @Override
+  public BarCreate id(@javax.annotation.Nullable String id) {
+    this.setId(id);
+    return this;
+  }
+
+  @Override
+  public BarCreate atSchemaLocation(@javax.annotation.Nullable String atSchemaLocation) {
+    this.setAtSchemaLocation(atSchemaLocation);
+    return this;
+  }
+
+  @Override
+  public BarCreate atBaseType(@javax.annotation.Nullable String atBaseType) {
+    this.setAtBaseType(atBaseType);
+    return this;
+  }
+
+  @Override
+  public BarCreate atType(@javax.annotation.Nonnull String atType) {
+    this.setAtType(atType);
+    return this;
+  }
+
   @Override
   public boolean equals(Object o) {
     if (this == o) {

samples/client/others/java/webclient-sealedInterface/src/main/java/org/openapitools/client/model/BarRef.java

@@ -45,6 +45,48 @@ public BarRef() {
   }
 
 
+  @Override
+  public BarRef href(@javax.annotation.Nullable String href) {
+    this.setHref(href);
+    return this;
+  }
+
+  @Override
+  public BarRef id(@javax.annotation.Nullable String id) {
+    this.setId(id);
+    return this;
+  }
+
+  @Override
+  public BarRef atSchemaLocation(@javax.annotation.Nullable String atSchemaLocation) {
+    this.setAtSchemaLocation(atSchemaLocation);
+    return this;
+  }
+
+  @Override
+  public BarRef atBaseType(@javax.annotation.Nullable String atBaseType) {
+    this.setAtBaseType(atBaseType);
+    return this;
+  }
+
+  @Override
+  public BarRef atType(@javax.annotation.Nonnull String atType) {
+    this.setAtType(atType);
+    return this;
+  }
+
+  @Override
+  public BarRef name(@javax.annotation.Nullable String name) {
+    this.setName(name);
+    return this;
+  }
+
+  @Override
+  public BarRef atReferredType(@javax.annotation.Nullable String atReferredType) {
+    this.setAtReferredType(atReferredType);
+    return this;
+  }
+
   @Override
   public boolean equals(Object o) {
     if (this == o) {

samples/client/others/java/webclient-sealedInterface/src/main/java/org/openapitools/client/model/Foo.java

@@ -105,6 +105,36 @@ public void setFooPropB(@javax.annotation.Nullable String fooPropB) {
   }
 
 
+  @Override
+  public Foo href(@javax.annotation.Nullable String href) {
+    this.setHref(href);
+    return this;
+  }
+
+  @Override
+  public Foo id(@javax.annotation.Nullable String id) {
+    this.setId(id);
+    return this;
+  }
+
+  @Override
+  public Foo atSchemaLocation(@javax.annotation.Nullable String atSchemaLocation) {
+    this.setAtSchemaLocation(atSchemaLocation);
+    return this;
+  }
+
+  @Override
+  public Foo atBaseType(@javax.annotation.Nullable String atBaseType) {
+    this.setAtBaseType(atBaseType);
+    return this;
+  }
+
+  @Override
+  public Foo atType(@javax.annotation.Nonnull String atType) {
+    this.setAtType(atType);
+    return this;
+  }
+
   @Override
   public boolean equals(Object o) {
     if (this == o) {

samples/client/others/java/webclient-sealedInterface/src/main/java/org/openapitools/client/model/FooRef.java

@@ -75,6 +75,48 @@ public void setFoorefPropA(@javax.annotation.Nullable String foorefPropA) {
   }
 
 
+  @Override
+  public FooRef href(@javax.annotation.Nullable String href) {
+    this.setHref(href);
+    return this;
+  }
+
+  @Override
+  public FooRef id(@javax.annotation.Nullable String id) {
+    this.setId(id);
+    return this;
+  }
+
+  @Override
+  public FooRef atSchemaLocation(@javax.annotation.Nullable String atSchemaLocation) {
+    this.setAtSchemaLocation(atSchemaLocation);
+    return this;
+  }
+
+  @Override
+  public FooRef atBaseType(@javax.annotation.Nullable String atBaseType) {
+    this.setAtBaseType(atBaseType);
+    return this;
+  }
+
+  @Override
+  public FooRef atType(@javax.annotation.Nonnull String atType) {
+    this.setAtType(atType);
+    return this;
+  }
+
+  @Override
+  public FooRef name(@javax.annotation.Nullable String name) {
+    this.setName(name);
+    return this;
+  }
+
+  @Override
+  public FooRef atReferredType(@javax.annotation.Nullable String atReferredType) {
+    this.setAtReferredType(atReferredType);
+    return this;
+  }
+
   @Override
   public boolean equals(Object o) {
     if (this == o) {

samples/client/others/java/webclient-sealedInterface/src/main/java/org/openapitools/client/model/Pasta.java

@@ -75,6 +75,36 @@ public void setVendor(@javax.annotation.Nullable String vendor) {
   }
 
 
+  @Override
+  public Pasta href(@javax.annotation.Nullable String href) {
+    this.setHref(href);
+    return this;
+  }
+
+  @Override
+  public Pasta id(@javax.annotation.Nullable String id) {
+    this.setId(id);
+    return this;
+  }
+
+  @Override
+  public Pasta atSchemaLocation(@javax.annotation.Nullable String atSchemaLocation) {
+    this.setAtSchemaLocation(atSchemaLocation);
+    return this;
+  }
+
+  @Override
+  public Pasta atBaseType(@javax.annotation.Nullable String atBaseType) {
+    this.setAtBaseType(atBaseType);
+    return this;
+  }
+
+  @Override
+  public Pasta atType(@javax.annotation.Nonnull String atType) {
+    this.setAtType(atType);
+    return this;
+  }
+
   @Override
   public boolean equals(Object o) {
     if (this == o) {