From 05f9129cbe1e242c436fcb9f0d606362edf38bc1 Mon Sep 17 00:00:00 2001
From: Hugo Mercado <hugo.mario.mercado@gmail.com>
Date: Fri, 25 Aug 2023 23:57:41 -0500
Subject: [PATCH] allow null values for extensions properties in openapi object

---
 .../v3/core/jackson/mixin/OpenAPIMixin.java      |  2 ++
 .../serialization/JsonSerializationTest.java     | 16 ++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/modules/swagger-core/src/main/java/io/swagger/v3/core/jackson/mixin/OpenAPIMixin.java b/modules/swagger-core/src/main/java/io/swagger/v3/core/jackson/mixin/OpenAPIMixin.java
index b2296e8b39..d495abf326 100644
--- a/modules/swagger-core/src/main/java/io/swagger/v3/core/jackson/mixin/OpenAPIMixin.java
+++ b/modules/swagger-core/src/main/java/io/swagger/v3/core/jackson/mixin/OpenAPIMixin.java
@@ -3,6 +3,7 @@
 import com.fasterxml.jackson.annotation.JsonAnyGetter;
 import com.fasterxml.jackson.annotation.JsonAnySetter;
 import com.fasterxml.jackson.annotation.JsonIgnore;
+import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.databind.annotation.JsonSerialize;
 import io.swagger.v3.core.jackson.PathsSerializer;
 import io.swagger.v3.oas.models.PathItem;
@@ -12,6 +13,7 @@
 public abstract class OpenAPIMixin {
 
     @JsonAnyGetter
+    @JsonInclude
     public abstract Map<String, Object> getExtensions();
 
     @JsonAnySetter
diff --git a/modules/swagger-core/src/test/java/io/swagger/v3/core/serialization/JsonSerializationTest.java b/modules/swagger-core/src/test/java/io/swagger/v3/core/serialization/JsonSerializationTest.java
index 2cc3c5deab..29163d0cca 100644
--- a/modules/swagger-core/src/test/java/io/swagger/v3/core/serialization/JsonSerializationTest.java
+++ b/modules/swagger-core/src/test/java/io/swagger/v3/core/serialization/JsonSerializationTest.java
@@ -18,6 +18,9 @@
 import org.testng.annotations.Test;
 import org.yaml.snakeyaml.LoaderOptions;
 
+import java.util.HashMap;
+import java.util.Map;
+
 import static org.testng.Assert.assertEquals;
 import static org.testng.Assert.assertFalse;
 
@@ -55,6 +58,19 @@ public void testExtension() throws Exception {
 
     }
 
+    @Test
+    public void testExtensionObjectWithProperties() throws Exception {
+        final Map<String, Object> extensionObjectProps = new HashMap<>();
+        extensionObjectProps.put("x-foo-bar", "foo bar");
+        extensionObjectProps.put("x-bar-foo", null);
+
+        OpenAPI swagger = new OpenAPI();
+        swagger.addExtension("x-extension-with-properties", extensionObjectProps);
+
+        String swaggerJson = Json.mapper().writeValueAsString(swagger);
+        assertEquals(swaggerJson, "{\"openapi\":\"3.0.1\",\"x-extension-with-properties\":{\"x-foo-bar\":\"foo bar\",\"x-bar-foo\":null}}");
+    }
+
     @Test
     public void testSerializeASpecWithResponseReferences() throws Exception {
         OpenAPI swagger = new OpenAPI()