fix: deduplicate methods in JavassistProxy to prevent DuplicateMemberException

core-impl/proxy/src/main/java/com/alipay/sofa/rpc/proxy/javassist/JavassistProxy.java

@@ -42,8 +42,10 @@
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.util.ArrayList;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicInteger;
 
@@ -154,12 +156,22 @@ private void createMethod(Class<?> interfaceClass, List<String> fieldList, List<
         Method[] methodAry = interfaceClass.getMethods();
         StringBuilder sb = new StringBuilder(512);
         int mi = 0;
+        // Track method signatures to skip duplicate methods from multiple parent interfaces.
+        // When an interface extends multiple parent interfaces that declare the same method,
+        // interfaceClass.getMethods() returns duplicates, causing Javassist to throw
+        // DuplicateMemberException when adding the same method twice.
+        // See: https://github.com/sofastack/sofa-rpc/issues/1384
+        Set<String> addedMethodSignatures = new HashSet<String>();
         for (Method m : methodAry) {
-            mi++;
             if (Modifier.isNative(m.getModifiers()) || Modifier.isFinal(m.getModifiers()) ||
                 Modifier.isStatic(m.getModifiers())) {
                 continue;
             }
+            // Skip duplicate methods inherited from multiple parent interfaces
+            if (!addedMethodSignatures.add(buildMethodSignature(m))) {
+                continue;
+            }
+            mi++;
             Class<?>[] mType = m.getParameterTypes();
             Class<?> returnType = m.getReturnType();
 
@@ -285,6 +297,28 @@ public Invoker getInvoker(Object proxyObject) {
         return parseInvoker(proxyObject);
     }
 
+    /**
+     * Builds a unique method signature string in the format: methodName(paramType1,paramType2,...)
+     * Used to deduplicate methods inherited from multiple parent interfaces that declare the same method.
+     * Without deduplication, Javassist throws DuplicateMemberException when the same method is added twice.
+     *
+     * @param method the method to build a signature for
+     * @return the method signature string
+     */
+    private String buildMethodSignature(Method method) {
+        StringBuilder signature = new StringBuilder(method.getName());
+        signature.append('(');
+        Class<?>[] parameterTypes = method.getParameterTypes();
+        for (int i = 0; i < parameterTypes.length; i++) {
+            if (i > 0) {
+                signature.append(',');
+            }
+            signature.append(parameterTypes[i].getName());
+        }
+        signature.append(')');
+        return signature.toString();
+    }
+
     /**
      * Parse proxy invoker from proxy object
      *