support serialize protobuf object

core/pom.xml

@@ -117,6 +117,11 @@
             <artifactId>guava</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>com.google.protobuf</groupId>
+            <artifactId>protobuf-java</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>com.jayway.jsonpath</groupId>
             <artifactId>json-path</artifactId>

core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterCreatorASM.java

@@ -185,6 +185,20 @@ public class ObjectWriterCreatorASM
         }
 
         boolean record = BeanUtils.isRecord(objectClass);
+        Class superClass = objectClass.getSuperclass();
+        boolean protobufMessageV3 = superClass != null && superClass.getName().equals("com.google.protobuf.GeneratedMessageV3");
+        Class superClass1, superClass2;
+        if (protobufMessageV3) {
+            superClass1 = superClass.getSuperclass();
+            if (superClass1 != null) {
+                superClass2 = superClass1.getSuperclass();
+            } else {
+                superClass2 = null;
+            }
+        } else {
+            superClass1 = null;
+            superClass2 = null;
+        }
 
         List<FieldWriter> fieldWriters;
         if (fieldBased && !record) {
@@ -195,6 +209,19 @@ public class ObjectWriterCreatorASM
                     return;
                 }
 
+                Class<?> declaring = field.getDeclaringClass();
+                if (protobufMessageV3) {
+                    if (declaring == superClass || declaring == superClass1 || declaring == superClass2) {
+                        return;
+                    }
+                    String fieldName = field.getName();
+                    Class<?> fieldClass = field.getType();
+                    if ("cardsmap_".equals(fieldName) && fieldClass.getName().equals("com.google.protobuf.MapField")) {
+                        return;
+                    }
+                    //cardsmap_
+                }
+
                 fieldInfo.init();
                 FieldWriter fieldWriter = creteFieldWriter(objectClass, writerFeatures, provider.modules, beanInfo, fieldInfo, field);
                 if (fieldWriter != null) {

core/src/test/java/com/alibaba/fastjson2/dubbo/GoogleProtobufBasicTest.java

@@ -0,0 +1,30 @@
+package com.alibaba.fastjson2.dubbo;
+
+import com.alibaba.fastjson2.JSONB;
+import com.alibaba.fastjson2.JSONWriter;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+public class GoogleProtobufBasicTest {
+    @Test
+    public void test() {
+        GoogleProtobufBasic.GooglePBRequestType requestType = GoogleProtobufBasic.GooglePBRequestType.newBuilder()
+                .setString("some string from client")
+                .build();
+        JSONWriter.Feature[] features = {
+                JSONWriter.Feature.WriteClassName,
+                JSONWriter.Feature.FieldBased,
+                JSONWriter.Feature.ReferenceDetection,
+                JSONWriter.Feature.WriteNulls,
+                JSONWriter.Feature.NotWriteDefaultValue,
+                JSONWriter.Feature.NotWriteHashMapArrayListClassName,
+                JSONWriter.Feature.WriteNameAsSymbol
+        };
+        byte[] jsonbBytes = JSONB.toBytes(
+                requestType,
+                features
+        );
+        assertNotNull(jsonbBytes);
+    }
+}

pom.xml

@@ -612,7 +612,8 @@
                                 com/alibaba/fastjson/issue_1300/Issue1367_jaxrs.java,
                                 com/fasterxml/jackson/core/*.java,
                                 com/fasterxml/jackson/databind/*.java,
-                                com/alibaba/fastjson2/adapter/http/*.java
+                                com/alibaba/fastjson2/adapter/http/*.java,
+                                com/alibaba/fastjson2/dubbo/GoogleProtobufBasic.java
                             </excludes>
                         </configuration>
                     </execution>