[Networkwatcer] add FlowLogFormatParameters (#4374)

* Update specification/network/resource-manager/Microsoft.Network/stable/2018-08-01/networkWatcher.json

[Networkwatcher] add a new field "Format" with new type"FlowLogFormat" to FlowLogProperties

* Revert "Update specification/network/resource-manager/Microsoft.Network/stable/2018-08-01/networkWatcher.json"

This reverts commit f4f438a.

* Update specification/network/resource-manager/Microsoft.Network/stable/2018-10-01/networkWatcher.json

[networkwatcer] add FlowLogFormatParameters

specification/network/resource-manager/Microsoft.Network/stable/2018-10-01/networkWatcher.json

@@ -2585,6 +2585,9 @@
         },
         "retentionPolicy": {
           "$ref": "#/definitions/RetentionPolicyParameters"
+        },
+        "format": {
+          "$ref": "#/definitions/FlowLogFormatParameters"
         }
       }
     },
@@ -2615,6 +2618,27 @@
         }
       }
     },
+    "FlowLogFormatParameters": {
+      "description": "Parameters that define the flow log format.",
+      "properties": {
+        "type": {
+          "type": "string",
+          "description": "The file type of flow log.",
+          "enum": [
+            "JSON"
+          ],
+          "x-ms-enum": {
+            "name": "FlowLogFormatType",
+            "modelAsString": true
+          }
+        },
+        "version": {
+          "description": "The version (revision) of the flow log.",
+          "type": "integer",
+          "default": 0
+        }
+      }
+    },
     "FlowLogInformation": {
       "description": "Information on the configuration of flow log and traffic analytics (optional) .",
       "required": [