Add support for links in Monitoring AlertPolicy (#11017)

Co-authored-by: Zhenhua Li <zhenhuali@google.com>

mmv1/products/monitoring/AlertPolicy.yaml

@@ -983,6 +983,7 @@ properties:
           - documentation.0.content
           - documentation.0.mime_type
           - documentation.0.subject
+          - documentation.0.links
         description: |
           The text of the documentation, interpreted according to mimeType.
           The content may not exceed 8,192 Unicode characters and may not
@@ -994,6 +995,7 @@ properties:
           - documentation.0.content
           - documentation.0.mime_type
           - documentation.0.subject
+          - documentation.0.links
         default_value: text/markdown
         description: |
           The format of the content field. Presently, only the value
@@ -1004,8 +1006,28 @@ properties:
           - documentation.0.content
           - documentation.0.mime_type
           - documentation.0.subject
+          - documentation.0.links
         description: |
           The subject line of the notification. The subject line may not
           exceed 10,240 bytes. In notifications generated by this policy the contents
           of the subject line after variable expansion will be truncated to 255 bytes
           or shorter at the latest UTF-8 character boundary.
+      - !ruby/object:Api::Type::Array
+        name: links
+        at_least_one_of:
+          - documentation.0.content
+          - documentation.0.mime_type
+          - documentation.0.subject
+          - documentation.0.links
+        description: |
+          Links to content such as playbooks, repositories, and other resources. This field can contain up to 3 entries.
+        item_type: !ruby/object:Api::Type::NestedObject
+          properties:
+            - !ruby/object:Api::Type::String
+              name: displayName
+              description: |
+                A short display name for the link. The display name must not be empty or exceed 63 characters. Example: "playbook".
+            - !ruby/object:Api::Type::String
+              name: url
+              description: |
+                The url of a webpage. A url can be templatized by using variables in the path or the query parameters. The total length of a URL should not exceed 2083 characters before and after variable expansion. Example: "https://my_domain.com/playbook?name=${resource.name}".

mmv1/third_party/terraform/services/monitoring/resource_monitoring_alert_policy_test.go

@@ -329,6 +329,10 @@ resource "google_monitoring_alert_policy" "full" {
     content   = "test content"
     mime_type = "text/markdown"
     subject = "test subject"
+    links {
+        display_name = "link display name"
+        url = "http://mydomain.com"
+    }
   }
 }
 `, alertName, conditionName1, conditionName2)
@@ -360,6 +364,14 @@ resource "google_monitoring_alert_policy" "mql" {
     content   = "test content"
     mime_type = "text/markdown"
     subject = "test subject"
+    links {
+        display_name = "link display name"
+        url = "http://mydomain.com"
+    }
+    links {
+        display_name = "link display name2"
+        url = "http://mydomain2.com"
+    }
   }
 }
 `, alertName, conditionName)
@@ -395,7 +407,7 @@ resource "google_monitoring_alert_policy" "log" {
   documentation {
     content   = "test content"
     mime_type = "text/markdown"
-    subject = "test subject"    
+    subject = "test subject"
   }
 }
 `, alertName, conditionName)
@@ -457,6 +469,10 @@ resource "google_monitoring_alert_policy" "promql" {
     content   = "test content"
     mime_type = "text/markdown"
     subject = "test subject"
+    links {
+        display_name = "link display name"
+        url = "http://mydomain.com"
+    }
   }
 }
 `, alertName, conditionName)