Kotlin enums are always marked as required if used in Java controllers.

Fixes #2622

springdoc-openapi-starter-common/src/main/java/org/springdoc/core/configuration/SpringDocKotlinConfiguration.kt

@@ -92,9 +92,13 @@ class SpringDocKotlinConfiguration() {
 					// parameter is not required if a default value is provided in @RequestParam
 					else if (requestParam != null && requestParam.defaultValue != ValueConstants.DEFAULT_NONE)
 						parameterModel.required = false
-					else
+					else{
+						val isJavaNullableAnnotationPresent = methodParameter.parameterAnnotations.any {
+							it.annotationClass.qualifiedName == "jakarta.annotation.Nullable"
+						}
 						parameterModel.required =
-							kParameter.type.isMarkedNullable == false
+							kParameter.type.isMarkedNullable == false && !isJavaNullableAnnotationPresent
+					}
 				}
 			}
 			return@ParameterCustomizer parameterModel

springdoc-openapi-tests/springdoc-openapi-kotlin-webmvc-tests/src/test/kotlin/test/org/springdoc/api/app12/EnumController.java

@@ -0,0 +1,18 @@
+package test.org.springdoc.api.app12;
+
+import jakarta.annotation.Nullable;
+import test.org.springdoc.api.app12.SpringDocApp12Test.MyEnum;
+
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+/**
+ * @author bnasslahsen
+ */
+@RestController
+public class EnumController {
+	@GetMapping("/test-enum-2")
+	String testEnum2(@Nullable MyEnum e) {
+		return "";
+	}
+}

springdoc-openapi-tests/springdoc-openapi-kotlin-webmvc-tests/src/test/kotlin/test/org/springdoc/api/app12/SpringDocApp12Test.kt

@@ -0,0 +1,35 @@
+/*
+ *
+ *  * Copyright 2019-2023 the original author or authors.
+ *  *
+ *  * Licensed under the Apache License, Version 2.0 (the "License");
+ *  * you may not use this file except in compliance with the License.
+ *  * You may obtain a copy of the License at
+ *  *
+ *  *      https://www.apache.org/licenses/LICENSE-2.0
+ *  *
+ *  * Unless required by applicable law or agreed to in writing, software
+ *  * distributed under the License is distributed on an "AS IS" BASIS,
+ *  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  * See the License for the specific language governing permissions and
+ *  * limitations under the License.
+ *
+ */
+
+package test.org.springdoc.api.app12
+
+import org.springframework.boot.autoconfigure.SpringBootApplication
+import org.springframework.context.annotation.ComponentScan
+import test.org.springdoc.api.AbstractKotlinSpringDocMVCTest
+
+class SpringDocApp12Test : AbstractKotlinSpringDocMVCTest() {
+
+	@SpringBootApplication
+	@ComponentScan(basePackages = ["org.springdoc", "test.org.springdoc.api.app12"])
+	class DemoApplication
+
+	enum class MyEnum {
+		A, B;
+	}
+
+}

springdoc-openapi-tests/springdoc-openapi-kotlin-webmvc-tests/src/test/resources/results/app12.json

@@ -0,0 +1,50 @@
+{
+  "openapi": "3.0.1",
+  "info": {
+    "title": "OpenAPI definition",
+    "version": "v0"
+  },
+  "servers": [
+    {
+      "url": "http://localhost",
+      "description": "Generated server url"
+    }
+  ],
+  "paths": {
+    "/test-enum-2": {
+      "get": {
+        "tags": [
+          "enum-controller"
+        ],
+        "operationId": "testEnum2",
+        "parameters": [
+          {
+            "name": "e",
+            "in": "query",
+            "required": false,
+            "schema": {
+              "type": "string",
+              "enum": [
+                "A",
+                "B"
+              ]
+            }
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "OK",
+            "content": {
+              "*/*": {
+                "schema": {
+                  "type": "string"
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  },
+  "components": {}
+}