add LoggingErrorHandlingGreeterClient with java (#289)

* add LoggingErrorHandlingGreeterClient with java

* handle exception

* format

* remove mark word

* update header

plugin-tester-java/src/main/java/example/myapp/helloworld/LoggingErrorHandlingGreeterClient.java

@@ -0,0 +1,79 @@
+/*
+ * 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 example.myapp.helloworld;
+
+import example.myapp.helloworld.grpc.GreeterServiceClient;
+import example.myapp.helloworld.grpc.HelloReply;
+import example.myapp.helloworld.grpc.HelloRequest;
+import java.util.concurrent.CompletionStage;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+import org.apache.pekko.actor.ActorSystem;
+import org.apache.pekko.grpc.GrpcClientSettings;
+
+public class LoggingErrorHandlingGreeterClient {
+
+  public static void main(String[] args) {
+
+    // Boot pekko
+    ActorSystem sys = ActorSystem.create("LoggingErrorHandlingGreeterClient");
+
+    // Take details how to connect to the service from the config.
+    GrpcClientSettings clientSettings =
+        GrpcClientSettings.connectToServiceAt("127.0.0.1", 8082, sys).withTls(false);
+    // Create a client-side stub for the service
+    GreeterServiceClient client = GreeterServiceClient.create(clientSettings, sys);
+
+    try {
+      HelloRequest Martin = HelloRequest.newBuilder().setName("Martin").build();
+      CompletionStage<HelloReply> successful = client.sayHello(Martin);
+      successful.toCompletableFuture().get(10, TimeUnit.SECONDS);
+      sys.log().info("Call succeeded");
+
+      HelloRequest martin = HelloRequest.newBuilder().setName("martin").build();
+      CompletionStage<HelloReply> failedBecauseLowercase = client.sayHello(martin);
+      failedBecauseLowercase
+          .handle(
+              (response, exception) -> {
+                if (exception != null) {
+                  sys.log().info("Call with lowercase name failed");
+                }
+                return response;
+              })
+          .toCompletableFuture()
+          .get(10, TimeUnit.SECONDS);
+
+      HelloRequest empty = HelloRequest.newBuilder().setName("").build();
+      CompletionStage<HelloReply> failedBecauseEmpty = client.sayHello(empty);
+      failedBecauseEmpty
+          .handle(
+              (response, exception) -> {
+                if (exception != null) {
+                  sys.log().info("Call with empty name failed");
+                }
+                return response;
+              })
+          .toCompletableFuture()
+          .get(10, TimeUnit.SECONDS);
+    } catch (InterruptedException | ExecutionException | TimeoutException e) {
+      throw new RuntimeException(e);
+    }
+    sys.terminate();
+  }
+}