[Service Bus] Bug Fix: Correlation Rule Filter with the "label" doesn't filter the messages (Azure#13069)

### BUG
Azure#13063
The correlation filter with the "subject" set using the `createRule` method doesn't filter the messages to the subscription. However, when we create the rule with the same correlation filter from the service bus explorer, messages get filtered as expected.

### CAUSE
The key-value pairs having undefined/null as the values can be present in the request object at any level. They get serialized as empty tags in the XML request for the ATOM management operations.

If such empty tags are present at the top level, the service throws a "Bad Request" error. This was handled by the SDK to make sure that the top-level of the request body doesn't have any empty tags.

If such empty tags are present at the inner levels, the service assigns the empty strings as values to the empty tags instead of throwing an error. This wasn't handled and the empty tags at the rule filter created an unexpected filter for the subscription. This PR attempts to fix this issue.

### FIX
The key-value pairs having undefined/null as the values are removed recursively from the object that is being serialized.

Author: HarshaNalluru

sdk/servicebus/service-bus/CHANGELOG.md

@@ -10,6 +10,8 @@
 - Updates documentation for `ServiceBusMessage` to call out that the `body` field
   must be converted to a byte array or `Buffer` when cross-language
   compatibility while receiving events is required.
+- [Bug Fix] Correlation Rule Filter with the "label" set using the `createRule()` method doesn't filter the messages to the subscription.
+  The bug has been fixed in [PR 13069](https://github.com/Azure/azure-sdk-for-js/pull/13069), also fixes the related issues where the messages are not filtered when a subset of properties are set in the correlation filter.
 
 ## 7.0.0 (2020-11-23)
 

sdk/servicebus/service-bus/src/util/atomXmlHelper.ts

@@ -19,6 +19,7 @@ import { administrationLogger as logger } from "../log";
 import { Buffer } from "buffer";
 
 import { parseURL } from "./parseUrl";
+import { isJSONLikeObject } from "./utils";
 
 /**
  * @internal
@@ -91,6 +92,28 @@ export async function executeAtomXmlOperation(
   return serializer.deserialize(response);
 }
 
+/**
+ * @internal
+ * @hidden
+ * The key-value pairs having undefined/null as the values would lead to the empty tags in the serialized XML request.
+ * Empty tags in the request body is problematic because of the following reasons.
+ * - ATOM based management operations throw a "Bad Request" error if empty tags are included in the XML request body at top level.
+ * - At the inner levels, Service assigns the empty strings as values to the empty tags instead of throwing an error.
+ *
+ * This method recursively removes the key-value pairs with undefined/null as the values from the request object that is to be serialized.
+ *
+ * @param {{ [key: string]: any }} resource
+ */
+export function sanitizeSerializableObject(resource: { [key: string]: any }) {
+  Object.keys(resource).forEach(function(property) {
+    if (resource[property] == undefined) {
+      delete resource[property];
+    } else if (isJSONLikeObject(resource[property])) {
+      sanitizeSerializableObject(resource[property]);
+    }
+  });
+}
+
 /**
  * @internal
  * @hidden
@@ -103,15 +126,8 @@ export async function executeAtomXmlOperation(
 export function serializeToAtomXmlRequest(resourceName: string, resource: any): object {
   const content: any = {};
 
-  // The top level key value pairs having undefined/null as the value are removed in order to address issue where the Service Bus'
-  // ATOM based management operations throw a "Bad Request" error if empty tags are included in the xml request body at top level.
-  const processedResource = Object.assign({}, resource);
-  Object.keys(processedResource).forEach(function(property) {
-    if (processedResource[property] == undefined) {
-      delete processedResource[property];
-    }
-  });
-  content[resourceName] = processedResource;
+  content[resourceName] = Object.assign({}, resource);
+  sanitizeSerializableObject(content[resourceName]);
 
   content[resourceName][Constants.XML_METADATA_MARKER] = {
     xmlns: "http://schemas.microsoft.com/netservices/2010/10/servicebus/connect",

sdk/servicebus/service-bus/src/util/utils.ts

@@ -282,14 +282,33 @@ export function getBooleanOrUndefined(value: any): boolean | undefined {
   );
 }
 
+/**
+ * @internal
+ * @hidden
+ * Helps in differentiating JSON like objects from other kinds of objects.
+ */
+const EMPTY_JSON_OBJECT_CONSTRUCTOR = {}.constructor;
+
 /**
  * @internal
  * @hidden
  * Returns `true` if given input is a JSON like object.
  * @param value
  */
 export function isJSONLikeObject(value: any): boolean {
-  return typeof value === "object" && !(value instanceof Number) && !(value instanceof String);
+  // `value.constructor === {}.constructor` differentiates among the "object"s,
+  //    would filter the JSON objects and won't match any array or other kinds of objects
+
+  // -------------------------------------------------------------------------------
+  // Few examples       | typeof obj ==="object" |  obj.constructor==={}.constructor
+  // -------------------------------------------------------------------------------
+  // {abc:1}            | true                   | true
+  // ["a","b"]          | true                   | false
+  // [{"a":1},{"b":2}]  | true                   | false
+  // new Date()         | true                   | false
+  // 123                | false                  | false
+  // -------------------------------------------------------------------------------
+  return typeof value === "object" && value.constructor === EMPTY_JSON_OBJECT_CONSTRUCTOR;
 }
 
 /**