Regression: @Header(schema = @Schema(type = "string")) generates empty or broken schema in OpenAPI output since 2.8.0. Fixes #2972

Author: bnasslahsen

springdoc-openapi-starter-common/src/main/java/org/springdoc/core/service/GenericResponseService.java

@@ -408,7 +408,7 @@ private Map<String, ApiResponse> computeResponseFromDoc(Components components, M
 						apiResponse.extensions(extensions);
 					}
 				}
-				AnnotationsUtils.getHeaders(apiResponseAnnotations.headers(), components, methodAttributes.getJsonViewAnnotation(), openapi31)
+				SpringDocAnnotationsUtils.getHeaders(apiResponseAnnotations.headers(), components, methodAttributes.getJsonViewAnnotation(), openapi31)
 						.ifPresent(apiResponse::headers);
 				apiResponsesOp.addApiResponse(httpCode, apiResponse);
 			}

springdoc-openapi-starter-common/src/main/java/org/springdoc/core/service/OperationService.java

@@ -337,7 +337,7 @@ private Optional<ApiResponses> getApiResponses(
 
 			buildResponseContent(methodAttributes, components, classProduces, methodProduces, apiResponsesOp, response, apiResponseObject);
 
-			AnnotationsUtils.getHeaders(response.headers(), components, null, propertyResolverUtils.isOpenapi31()).ifPresent(apiResponseObject::headers);
+			SpringDocAnnotationsUtils.getHeaders(response.headers(), components, null, propertyResolverUtils.isOpenapi31()).ifPresent(apiResponseObject::headers);
 			// Make schema as string if empty
 			calculateHeader(apiResponseObject);
 			if (isResponseObject(apiResponseObject)) {

springdoc-openapi-starter-common/src/main/java/org/springdoc/core/utils/SpringDocAnnotationsUtils.java

@@ -53,6 +53,7 @@
 import io.swagger.v3.oas.annotations.media.SchemaProperty;
 import io.swagger.v3.oas.models.Components;
 import io.swagger.v3.oas.models.SpecVersion;
+import io.swagger.v3.oas.models.headers.Header;
 import io.swagger.v3.oas.models.media.ArraySchema;
 import io.swagger.v3.oas.models.media.ComposedSchema;
 import io.swagger.v3.oas.models.media.Content;
@@ -481,4 +482,18 @@ public static Object resolveDefaultValue(String defaultValueStr, ObjectMapper ob
 		}
 		return defaultValue;
 	}
+
+	public static Optional<Map<String, Header>> getHeaders(io.swagger.v3.oas.annotations.headers.Header[] annotationHeaders, Components components, JsonView jsonViewAnnotation, boolean openapi31) {
+		Optional<Map<String, Header>> headerMap = AnnotationsUtils.getHeaders(annotationHeaders, components, jsonViewAnnotation, openapi31);
+		if(openapi31){
+			headerMap.ifPresent(map -> {
+				for (Entry<String, Header> entry : map.entrySet()) {
+					Header header = entry.getValue();
+					Schema schema = header.getSchema();
+					handleSchemaTypes(schema);
+				}
+			});
+		}
+		return headerMap;
+	}
 }

springdoc-openapi-starter-webmvc-api/src/test/java/test/org/springdoc/api/v31/app244/HelloController.java

@@ -0,0 +1,53 @@
+/*
+ *
+ *  *
+ *  *  *
+ *  *  *  *
+ *  *  *  *  *
+ *  *  *  *  *  * Copyright 2019-2025 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.v31.app244;
+
+import io.swagger.v3.oas.annotations.headers.Header;
+import io.swagger.v3.oas.annotations.media.Schema;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/test")
+public class HelloController {
+
+	@PostMapping
+	@ApiResponse(
+			responseCode = "201",
+			description = "Created",
+			headers = {
+					@Header(name = "Location", required = true, schema = @Schema(type = "string"))
+			}
+	)
+	public void uploadMultipartWithBody(){
+	}
+	
+
+}

springdoc-openapi-starter-webmvc-api/src/test/java/test/org/springdoc/api/v31/app244/SpringDocApp244Test.java

@@ -0,0 +1,37 @@
+/*
+ *
+ *  *
+ *  *  *
+ *  *  *  *
+ *  *  *  *  *
+ *  *  *  *  *  * Copyright 2019-2025 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.v31.app244;
+
+import test.org.springdoc.api.v31.AbstractSpringDocTest;
+
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+public class SpringDocApp244Test extends AbstractSpringDocTest {
+
+	@SpringBootApplication
+	static class SpringDocTestApp {}
+}

springdoc-openapi-starter-webmvc-api/src/test/resources/results/3.1.0/app244.json

@@ -0,0 +1,38 @@
+{
+  "openapi": "3.1.0",
+  "info": {
+    "title": "OpenAPI definition",
+    "version": "v0"
+  },
+  "servers": [
+    {
+      "url": "http://localhost",
+      "description": "Generated server url"
+    }
+  ],
+  "paths": {
+    "/test": {
+      "post": {
+        "tags": [
+          "hello-controller"
+        ],
+        "operationId": "uploadMultipartWithBody",
+        "responses": {
+          "201": {
+            "description": "Created",
+            "headers": {
+              "Location": {
+                "required": true,
+                "style": "simple",
+                "schema": {
+                  "type": "string"
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  },
+  "components": {}
+}