[ReleasePR keyvault] [Hub Generated] Review request for Microsoft.KeyVault to add version preview/2021-06-01-preview (#1922)

Create to sync Azure/azure-rest-api-specs#16042
[ReCreate this PR](https://github.com/azure-resource-manager-schemas/compare/main...AzureSDKAutomation:sdkAuto/keyvault?expand=1)

Author: msftbot[bot]

schemas/2021-06-01-preview/Microsoft.KeyVault.json

@@ -592,6 +592,17 @@
           ],
           "description": "Expiry date in seconds since 1970-01-01T00:00:00Z."
         },
+        "exportable": {
+          "oneOf": [
+            {
+              "type": "boolean"
+            },
+            {
+              "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
+            }
+          ],
+          "description": "Indicates if the private key can be exported."
+        },
         "nbf": {
           "oneOf": [
             {
@@ -687,6 +698,16 @@
           ],
           "description": "The type of the key. For valid values, see JsonWebKeyType."
         },
+        "release_policy": {
+          "oneOf": [
+            {
+              "$ref": "#/definitions/KeyReleasePolicy"
+            },
+            {
+              "$ref": "https://schema.management.azure.com/schemas/common/definitions.json#/definitions/expression"
+            }
+          ]
+        },
         "rotationPolicy": {
           "oneOf": [
             {
@@ -700,6 +721,21 @@
       },
       "description": "The properties of the key."
     },
+    "KeyReleasePolicy": {
+      "type": "object",
+      "properties": {
+        "contentType": {
+          "type": "string",
+          "default": "application/json; charset=utf-8",
+          "description": "Content type and version of key release policy"
+        },
+        "data": {
+          "type": "string",
+          "format": "base64url",
+          "description": "Blob encoding the policy rules under which the key can be released."
+        }
+      }
+    },
     "KeyRotationPolicyAttributes": {
       "type": "object",
       "properties": {