Add branches_to_be_notified param to hangouts

The API documentation says that it is possible to update
branches_to_be_notified via API but the endpoint was not
accepting the parameter. This commit adds support for
branches_to_be_notified

changelogs/unreleased/220503_bug_add_branches_to_be_notified_to_hangouts_service_api.yml

+---
+title: Fix branches_to_be_notified API param for hangouts chat service
+merge_request: 35599
+author:
+type: fixed

doc/api/services.md

@@ -659,7 +659,7 @@ Parameters:
 | `webhook` | string | true | The Hangouts Chat webhook. For example, `https://chat.googleapis.com/v1/spaces...`. |
 | `notify_only_broken_pipelines` | boolean | false | Send notifications for broken pipelines |
 | `notify_only_default_branch` | boolean | false | DEPRECATED: This parameter has been replaced with `branches_to_be_notified` |
-| `branches_to_be_notified` | string | all | Branches to send notifications for. Valid options are "all", "default", "protected", and "default_and_protected" |
+| `branches_to_be_notified` | string | false | Branches to send notifications for. Valid options are "all", "default", "protected", and "default_and_protected" |
 | `push_events` | boolean | false | Enable notifications for push events |
 | `issues_events` | boolean | false | Enable notifications for issue events |
 | `confidential_issues_events` | boolean | false | Enable notifications for confidential issue events |

lib/api/helpers/services_helpers.rb

@@ -381,6 +381,12 @@ module API
               type: String,
               desc: 'The Hangouts Chat webhook. e.g. https://chat.googleapis.com/v1/spaces…'
             },
+            {
+              required: false,
+              name: :branches_to_be_notified,
+              type: String,
+              desc: 'Branches for which notifications are to be sent'
+            },
             chat_notification_events
           ].flatten,
           'hipchat' => [

spec/requests/api/services_spec.rb

@@ -264,4 +264,34 @@ RSpec.describe API::Services do
       expect(json_response['properties']['notify_only_broken_pipelines']).to eq(true)
     end
   end
+
+  describe 'Hangouts Chat service' do
+    let(:service_name) { 'hangouts-chat' }
+    let(:params) do
+      {
+        webhook: 'https://hook.example.com',
+        branches_to_be_notified: 'default'
+      }
+    end
+
+    before do
+      project.create_hangouts_chat_service(
+        active: true,
+        properties: params
+      )
+    end
+
+    it 'accepts branches_to_be_notified for update', :aggregate_failures do
+      put api("/projects/#{project.id}/services/#{service_name}", user), params: params.merge(branches_to_be_notified: 'all')
+
+      expect(response).to have_gitlab_http_status(:ok)
+      expect(json_response['properties']['branches_to_be_notified']).to eq('all')
+    end
+
+    it 'only requires the webhook param' do
+      put api("/projects/#{project.id}/services/#{service_name}", user), params: { webhook: 'https://hook.example.com' }
+
+      expect(response).to have_gitlab_http_status(:ok)
+    end
+  end
 end