Fix UT error following PR #3527

Author: chickenlj

dubbo-compatible/src/test/java/org/apache/dubbo/common/extension/MockDispatcher.java

@@ -0,0 +1,29 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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
+ *
+ *      http://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 org.apache.dubbo.common.extension;
+
+import org.apache.dubbo.common.URL;
+import org.apache.dubbo.remoting.ChannelHandler;
+import org.apache.dubbo.remoting.Dispatcher;
+
+public class MockDispatcher implements Dispatcher {
+    @Override
+    public ChannelHandler dispatch(ChannelHandler handler, URL url) {
+        return null;
+    }
+}

dubbo-compatible/src/test/resources/META-INF/services/org.apache.dubbo.remoting.Dispatcher

@@ -0,0 +1,18 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You 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
+#
+#      http://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.
+#
+
+mockdispatcher=org.apache.dubbo.common.extension.MockDispatcher