fix: treat top-level array schemas with non-trivial items as real models, not aliases

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

@@ -969,7 +969,32 @@ public static boolean shouldGenerateMapModel(Schema schema) {
     }
 
     public static boolean shouldGenerateArrayModel(Schema schema) {
-        return ModelUtils.isGenerateAliasAsModel(schema) || !(schema.getProperties() == null || schema.getProperties().isEmpty());
+        if (ModelUtils.isGenerateAliasAsModel(schema)) {
+            return true;
+        }
+        // Generate if the array schema itself has properties (unusual but valid)
+        if (schema.getProperties() != null && !schema.getProperties().isEmpty()) {
+            return true;
+        }
+        // Generate if items are non-trivial (not a simple primitive alias like List<String>).
+        // After InlineModelResolver runs, complex inline items are extracted to components
+        // and replaced with a $ref, so we check for $ref as well as inline properties.
+        Schema<?> items = schema.getItems();
+        if (items != null) {
+            // Items resolved to a $ref (inline object was extracted to components)
+            if (items.get$ref() != null && !items.get$ref().isEmpty()) {
+                return true;
+            }
+            // Items with inline properties
+            if (items.getProperties() != null && !items.getProperties().isEmpty()) {
+                return true;
+            }
+            // Items with composed schema (oneOf/anyOf/allOf)
+            if (ModelUtils.isComposedSchema(items)) {
+                return true;
+            }
+        }
+        return false;
     }
 
     /**

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

@@ -598,7 +598,7 @@ public void testJdkHttpClientWithAndWithoutDiscriminator() {
         generator.setGeneratorPropertyDefault(CodegenConstants.APIS, "true");
         List<File> files = generator.opts(configurator.toClientOptInput()).generate();
 
-        assertThat(files).hasSize(153);
+        assertThat(files).hasSize(156);
         validateJavaSourceFiles(files);
         assertThat(output.resolve("src/main/java/xyz/abcdef/model/Dog.java")).content()
                 .contains("import xyz.abcdef.invoker.JSON;");

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

@@ -724,4 +724,60 @@ public void getParentNameMultipleInterfacesTest() {
         Schema composedSchema = allSchemas.get("RandomAnimalsResponse_animals_inner");
         assertNull(ModelUtils.getParentName(composedSchema, allSchemas));
     }
+
+    @Test
+    public void shouldGenerateArrayModelWithRefItems() {
+        // array with items.$ref should generate a model (most common case after InlineModelResolver)
+        Schema<?> items = new Schema<>();
+        items.set$ref("#/components/schemas/Foo");
+        Schema<?> arraySchema = new ArraySchema().items(items);
+        assertTrue(ModelUtils.shouldGenerateArrayModel(arraySchema));
+    }
+
+    @Test
+    public void shouldNotGenerateArrayModelWithPrimitiveItems() {
+        // array with simple string items is a plain alias (e.g. List<String>) — skip
+        Schema<?> arraySchema = new ArraySchema().items(new StringSchema());
+        assertFalse(ModelUtils.shouldGenerateArrayModel(arraySchema));
+    }
+
+    @Test
+    public void shouldNotGenerateArrayModelWithPrimitiveIntegerItems() {
+        // array with simple integer items is a plain alias (e.g. List<Integer>) — skip
+        Schema<?> arraySchema = new ArraySchema().items(new IntegerSchema());
+        assertFalse(ModelUtils.shouldGenerateArrayModel(arraySchema));
+    }
+
+    @Test
+    public void shouldGenerateArrayModelWithComposedItems() {
+        // array with oneOf items should generate a model
+        Schema<?> items = new Schema<>();
+        items.oneOf(List.of(new Schema<>().$ref("#/components/schemas/A"), new Schema<>().$ref("#/components/schemas/B")));
+        Schema<?> arraySchema = new ArraySchema().items(items);
+        assertTrue(ModelUtils.shouldGenerateArrayModel(arraySchema));
+    }
+
+    @Test
+    public void shouldGenerateArrayModelWithInlineObjectItems() {
+        // array with items that have inline properties should generate a model
+        Schema<?> items = new ObjectSchema();
+        items.addProperty("name", new StringSchema());
+        Schema<?> arraySchema = new ArraySchema().items(items);
+        assertTrue(ModelUtils.shouldGenerateArrayModel(arraySchema));
+    }
+
+    @Test
+    public void shouldNotGenerateArrayModelWithNullItems() {
+        // array with no items at all — alias, skip
+        Schema<?> arraySchema = new ArraySchema();
+        assertFalse(ModelUtils.shouldGenerateArrayModel(arraySchema));
+    }
+
+    @Test
+    public void shouldGenerateArrayModelWhenGenerateAliasAsModelExtensionIsSet() {
+        // with x-generate-alias-as-model extension, even a simple alias should generate
+        Schema<?> arraySchema = new ArraySchema().items(new StringSchema());
+        arraySchema.addExtension("x-generate-alias-as-model", true);
+        assertTrue(ModelUtils.shouldGenerateArrayModel(arraySchema));
+    }
 }