[core] Normalizer: x-items extension for List customization

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

@@ -1141,9 +1141,39 @@ protected void markSchemaAsVisited(Schema schema, Set<Schema> visitedSchemas) {
 
     protected Schema normalizeArraySchema(Schema schema) {
         Schema result = processNormalize31Spec(schema, new HashSet<>());
+
+        processExtensionsInRefItems(result);
         return processSetArraytoNullable(result);
     }
 
+    /**
+     * Move the extensions starting with x-items to the items.extensions.
+     *
+     * @param schema the array schema to process
+     */
+    protected void processExtensionsInRefItems(Schema schema) {
+        if (schema == null || schema.getItems() == null) {
+            return;
+        }
+
+        Map<String, Object> extensions = schema.getExtensions();
+        if (extensions != null) {
+            Map<String, Object> itemsExtensions = schema.getItems().getExtensions();
+            for  (Iterator<String> it = extensions.keySet().iterator(); it.hasNext(); ) {
+                String key = it.next();
+                if (key.startsWith("x-items-")) {
+                    if (itemsExtensions == null) {
+                        itemsExtensions = new LinkedHashMap<>();
+                        schema.getItems().setExtensions(itemsExtensions);
+                    }
+                    String newKey = key.substring("x-items-".length());
+                    itemsExtensions.put(newKey, extensions.get(key));
+                    it.remove();
+                }
+            }
+        }
+    }
+
     protected Schema normalizeMapSchema(Schema schema) {
         Schema result = processNormalize31Spec(schema, new HashSet<>());
         return processSetMapToNullable(result);

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

@@ -1248,9 +1248,15 @@ protected String getBeanValidation(Schema<?> items) {
             return "";
         }
 
-        if (items.get$ref() != null) {
+        String itemsRef = items.get$ref();
+        if (itemsRef == null && items.getAllOf() != null && items.getAllOf().size() == 1) {
+            // $ref with siblings is wrapped by the normalizer into allOf: [$ref]
+            // -> ensure that @Valid is used below
+            itemsRef = items.getAllOf().get(0).get$ref();
+        }
+        if (itemsRef != null) {
             Map<String, Schema> schemas = this.openAPI.getComponents().getSchemas();
-            String ref = ModelUtils.getSimpleRef(items.get$ref());
+            String ref = ModelUtils.getSimpleRef(itemsRef);
             if (ref != null) {
                 Schema<?> schema = schemas.get(ref);
                 // objects and oneOf/anyOf/allOf models cascade validation into their elements;

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

@@ -10185,7 +10185,9 @@ void listItems_annotated_with_x_field_extra_annotation() throws IOException {
                 .fileContains(
                         "private List<@NotNull @Size(max=50) String> listString",
                         "private List<@Min(0)Integer> listInteger",
-                        "private List<@Size(max=10) String> listCode"
+                        "private List<@Size(max=10) String> listCode",
+                        "private List<@NotEmpty @Valid Stubb> listRef",
+                        "private List<@NotEmpty @Valid SampleModelListInlineInner>"
                 );
     }
 
@@ -10201,6 +10203,8 @@ void listItems_with_additionalItemsAnnotations() throws IOException {
                 "private List<@Size(max=50) String> listStringNullable",
                 "private List<@NotNull @Valid Stubb> listSample",
                 "private List<@NotNull @Min(0)Integer> listInteger",
-                "private List<@NotNull @Size(max=10) String> listCode");
+                "private List<@NotNull @Size(max=10) String> listCode",
+                "private List<@NotNull @NotEmpty @Valid Stubb> listRef",
+                "private List<@NotNull @NotEmpty @Valid SampleModelListInlineInner>");
     }
 }

modules/openapi-generator/src/test/resources/3_0/issue_23705.yaml

@@ -43,4 +43,17 @@ components:
             allOf:
               - $ref: '#/components/schemas/Code'
             x-field-extra-annotation: '@Size(max=10)'
+        listRef:
+          type: array
+          x-items-x-field-extra-annotation: '@NotEmpty'
+          items:
+            $ref: '#/components/schemas/Stubb'
+        listInline:
+          type: array
+          x-items-x-field-extra-annotation: '@NotEmpty'
+          items:
+            type: object
+            properties:
+              name:
+                type: string