V3 modify revert

apm-sniffer/apm-sdk-plugin/mongodb-3.x-plugin/src/main/java/org/skywalking/apm/plugin/mongodb/v3/MongoDBMethodInterceptor.java

@@ -200,15 +200,7 @@ public class MongoDBMethodInterceptor implements InstanceMethodsAroundIntercepto
     public void onConstruct(EnhancedInstance objInst, Object[] allArguments) {
         Cluster cluster = (Cluster)allArguments[0];
         StringBuilder peers = new StringBuilder();
-        List<ServerDescription> servers;
-        try {
-            cluster.getDescription().getClass().getMethod("getServerDescriptions", null);
-            servers = cluster.getDescription().getServerDescriptions();
-
-        } catch (NoSuchMethodException e) {
-            servers = cluster.getDescription().getAny();
-        }
-        for (ServerDescription description : servers) {
+        for (ServerDescription description : cluster.getDescription().getServerDescriptions()) {
             ServerAddress address = description.getAddress();
             peers.append(address.getHost() + ":" + address.getPort() + ";");
         }