[Hub Generated] Review request for Microsoft.Portal to add version preview/2015-08-01-preview (#12732)

* Fixing properties in dashboard parts

* Updating Dashboard part metadata

* Updating based on prettier fixes

Co-authored-by: Himanshu Chandel <hich@microsoft.com>

Author: msHich

specification/portal/resource-manager/Microsoft.Portal/preview/2015-08-01-preview/portal.json

@@ -395,6 +395,11 @@
       },
       "description": "List of dashboards."
     },
+    "DashboardPartMetadata": {
+      "description": "A dashboard part metadata.",
+      "type": "object",
+      "additionalProperties": true
+    },
     "DashboardParts": {
       "type": "object",
       "description": "A dashboard part.",
@@ -438,11 +443,7 @@
           }
         },
         "metadata": {
-          "description": "The dashboard part's metadata.",
-          "type": "object",
-          "additionalProperties": {
-            "type": "object"
-          }
+          "$ref": "#/definitions/DashboardPartMetadata"
         }
       }
     },

specification/portal/resource-manager/Microsoft.Portal/preview/2018-10-01-preview/portal.json

@@ -395,6 +395,11 @@
       },
       "description": "List of dashboards."
     },
+    "DashboardPartMetadata": {
+      "description": "A dashboard part metadata.",
+      "type": "object",
+      "additionalProperties": true
+    },
     "DashboardParts": {
       "type": "object",
       "description": "A dashboard part.",
@@ -438,11 +443,7 @@
           }
         },
         "metadata": {
-          "description": "The dashboard part's metadata.",
-          "type": "object",
-          "additionalProperties": {
-            "type": "object"
-          }
+          "$ref": "#/definitions/DashboardPartMetadata"
         }
       }
     },

specification/portal/resource-manager/Microsoft.Portal/preview/2019-01-01-preview/portal.json

@@ -401,6 +401,11 @@
       },
       "description": "List of dashboards."
     },
+    "DashboardPartMetadata": {
+      "description": "A dashboard part metadata.",
+      "type": "object",
+      "additionalProperties": true
+    },
     "DashboardParts": {
       "type": "object",
       "description": "A dashboard part.",
@@ -448,11 +453,7 @@
           }
         },
         "metadata": {
-          "description": "The dashboard part's metadata.",
-          "type": "object",
-          "additionalProperties": {
-            "type": "object"
-          }
+          "$ref": "#/definitions/DashboardPartMetadata"
         }
       }
     },

specification/portal/resource-manager/Microsoft.Portal/preview/2020-09-01-preview/portal.json

@@ -460,6 +460,7 @@
         "type"
       ],
       "description": "A dashboard part metadata.",
+      "additionalProperties": true,
       "properties": {
         "type": {
           "type": "string",