Add GatewayTimeoutErrorStatus for HttpObservable errors

Author: wezhang

Utils/hdinsight-node-common/src/com/microsoft/azure/hdinsight/sdk/common/HttpObservable.java

@@ -301,6 +301,8 @@ public static HttpErrorStatus classifyHttpError(@NotNull CloseableHttpResponse h
             return new MethodNotAllowedHttpErrorStatus(message, headers, httpEntity);
         } else if (statusCode == 500) {
             return new InternalServerErrorHttpErrorStatus(message, headers, httpEntity);
+        } else if (statusCode == 504) {
+            return new GatewayTimeoutErrorStatus(message, headers, httpEntity);
         } else {
             return new UnclassifiedHttpErrorStatus(statusCode, message, headers, httpEntity);
         }

Utils/hdinsight-node-common/src/com/microsoft/azure/hdinsight/sdk/common/errorresponse/GatewayTimeoutErrorStatus.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) Microsoft Corporation
+ *
+ * All rights reserved.
+ *
+ * MIT License
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
+ * documentation files (the "Software"), to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and
+ * to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies or substantial portions of
+ * the Software.
+ *
+ * THE SOFTWARE IS PROVIDED *AS IS*, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO
+ * THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.microsoft.azure.hdinsight.sdk.common.errorresponse;
+
+import org.apache.http.Header;
+import org.apache.http.HttpEntity;
+
+import com.microsoft.azuretools.azurecommons.helpers.Nullable;
+
+public class GatewayTimeoutErrorStatus extends HttpErrorStatus {
+    public GatewayTimeoutErrorStatus(String message, @Nullable Header[] headers, @Nullable HttpEntity entity) {
+        super(504, message, headers, entity);
+    }
+}