[ISSUE #916] Add message body empty check for C# client

Author: tsunghanjacktsai

csharp/rocketmq-client-csharp/Error/PayloadEmptyException.cs

@@ -0,0 +1,34 @@
+/*
+ * 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.
+ */
+
+namespace Org.Apache.Rocketmq.Error
+{
+    /// <summary>
+    /// Generic exception represents when the request entity is empty.
+    /// </summary>
+    public class PayloadEmptyException : ClientException
+    {
+        public PayloadEmptyException(int responseCode, string requestId, string message) : base(responseCode,
+            requestId, message)
+        {
+        }
+
+        public PayloadEmptyException(int responseCode, string message) : base(responseCode, message)
+        {
+        }
+    }
+}

csharp/rocketmq-client-csharp/Message.cs

@@ -91,7 +91,7 @@ public Builder SetTopic(string topic)
 
             public Builder SetBody(byte[] body)
             {
-                Preconditions.CheckArgument(null != body, "body should not be null");
+                Preconditions.CheckArgument(null != body || body.Length == 0, "body should not be empty");
                 _body = body;
                 return this;
             }

csharp/rocketmq-client-csharp/StatusChecker.cs

@@ -77,6 +77,8 @@ public static void Check(Proto.Status status, IMessage request, string requestId
                 case Proto.Code.PayloadTooLarge:
                 case Proto.Code.MessageBodyTooLarge:
                     throw new PayloadTooLargeException((int)statusCode, requestId, statusMessage);
+                case Proto.Code.MessageBodyEmpty:
+                    throw new PayloadEmptyException((int)statusCode, requestId, statusMessage);
                 case Proto.Code.TooManyRequests:
                     throw new TooManyRequestsException((int)statusCode, requestId, statusMessage);
                 case Proto.Code.RequestHeaderFieldsTooLarge: