feat: add support for service directory webhooks

protos/google/cloud/dialogflow/cx/v3/webhook.proto

@@ -114,6 +114,26 @@ message Webhook {
     map<string, string> request_headers = 4;
   }
 
+  // Represents configuration for a [Service
+  // Directory](https://cloud.google.com/service-directory) service.
+  message ServiceDirectoryConfig {
+    // Required. The name of [Service
+    // Directory](https://cloud.google.com/service-directory) service.
+    // Format: `projects/<Project ID>/locations/<Location
+    // ID>/namespaces/<Namespace ID>/services/<Service ID>`.
+    // `Location ID` of the service directory must be the same as the location
+    // of the agent.
+    string service = 1 [
+      (google.api.field_behavior) = REQUIRED,
+      (google.api.resource_reference) = {
+        type: "servicedirectory.googleapis.com/Service"
+      }
+    ];
+
+    // Generic Service configuration of this webhook.
+    GenericWebService generic_web_service = 2;
+  }
+
   // The unique identifier of the webhook.
   // Required for the [Webhooks.UpdateWebhook][google.cloud.dialogflow.cx.v3.Webhooks.UpdateWebhook] method.
   // [Webhooks.CreateWebhook][google.cloud.dialogflow.cx.v3.Webhooks.CreateWebhook] populates the name automatically.
@@ -128,6 +148,10 @@ message Webhook {
   oneof webhook {
     // Configuration for a generic web service.
     GenericWebService generic_web_service = 4;
+
+    // Configuration for a [Service
+    // Directory](https://cloud.google.com/service-directory) service.
+    ServiceDirectoryConfig service_directory = 7;
   }
 
   // Webhook execution timeout. Execution is considered failed if Dialogflow