Fix ParameterizedType in SERVER_STREAM (#14763)

Author: AlbumenJ

dubbo-remoting/dubbo-remoting-http12/src/main/java/org/apache/dubbo/remoting/http12/message/MethodMetadata.java

@@ -21,6 +21,7 @@
 import org.apache.dubbo.rpc.model.StubMethodDescriptor;
 
 import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
 
 public class MethodMetadata {
 
@@ -64,18 +65,18 @@ private static MethodMetadata doResolveReflection(ReflectionMethodDescriptor met
             case CLIENT_STREAM:
             case BI_STREAM:
                 actualRequestTypes = new Class<?>[] {
-                    (Class<?>)
-                            ((ParameterizedType) method.getMethod().getGenericReturnType()).getActualTypeArguments()[0]
+                    obtainActualTypeInStreamObserver(
+                            ((ParameterizedType) method.getMethod().getGenericReturnType()).getActualTypeArguments()[0])
                 };
-                actualResponseType =
-                        (Class<?>) ((ParameterizedType) method.getMethod().getGenericParameterTypes()[0])
-                                .getActualTypeArguments()[0];
+                actualResponseType = obtainActualTypeInStreamObserver(
+                        ((ParameterizedType) method.getMethod().getGenericParameterTypes()[0])
+                                .getActualTypeArguments()[0]);
                 return new MethodMetadata(actualRequestTypes, actualResponseType);
             case SERVER_STREAM:
                 actualRequestTypes = new Class[] {method.getMethod().getParameterTypes()[0]};
-                actualResponseType =
-                        (Class<?>) ((ParameterizedType) method.getMethod().getGenericParameterTypes()[1])
-                                .getActualTypeArguments()[0];
+                actualResponseType = obtainActualTypeInStreamObserver(
+                        ((ParameterizedType) method.getMethod().getGenericParameterTypes()[1])
+                                .getActualTypeArguments()[0]);
                 return new MethodMetadata(actualRequestTypes, actualResponseType);
             case UNARY:
                 actualRequestTypes = method.getParameterClasses();
@@ -84,4 +85,11 @@ private static MethodMetadata doResolveReflection(ReflectionMethodDescriptor met
         }
         throw new IllegalStateException("Can not reach here");
     }
+
+    static Class<?> obtainActualTypeInStreamObserver(Type typeInStreamObserver) {
+        return (Class<?>)
+                (typeInStreamObserver instanceof ParameterizedType
+                        ? ((ParameterizedType) typeInStreamObserver).getRawType()
+                        : typeInStreamObserver);
+    }
 }