[Monitoring] Ensure the settings api always return the xpack/default_admin_email (#22220)

* If the settings collector returns nothing, ensure the settings api still returns a null value for default_admin_email

* Update test

* Feedback from PR

Author: chrisronline

x-pack/plugins/monitoring/server/kibana_monitoring/collectors/get_settings_collector.js

@@ -65,11 +65,7 @@ export function getSettingsCollector(server) {
 
       // skip everything if defaultAdminEmail === undefined
       if (defaultAdminEmail || (defaultAdminEmail === null && shouldUseNull)) {
-        kibanaSettingsData = {
-          xpack: {
-            default_admin_email: defaultAdminEmail
-          }
-        };
+        kibanaSettingsData = this.getEmailValueStructure(defaultAdminEmail);
         this.log.debug(`[${defaultAdminEmail}] default admin email setting found, sending [${KIBANA_SETTINGS_TYPE}] monitoring document.`);
       } else {
         this.log.debug(`not sending [${KIBANA_SETTINGS_TYPE}] monitoring document because [${defaultAdminEmail}] is null or invalid.`);
@@ -80,6 +76,13 @@ export function getSettingsCollector(server) {
 
       // returns undefined if there was no result
       return kibanaSettingsData;
+    },
+    getEmailValueStructure(email) {
+      return {
+        xpack: {
+          default_admin_email: email
+        }
+      };
     }
   });
 }

x-pack/plugins/xpack_main/server/routes/api/v1/settings.js

@@ -26,7 +26,10 @@ export function settingsRoute(server, kbnServer) {
         const { collectorSet } = server.usage;
         const settingsCollector = collectorSet.getCollectorByType(KIBANA_SETTINGS_TYPE);
 
-        const settings = await settingsCollector.fetch(callCluster);
+        let settings = await settingsCollector.fetch(callCluster);
+        if (!settings) {
+          settings = settingsCollector.getEmailValueStructure(null);
+        }
         const uuid = await getClusterUuid(callCluster);
 
         const kibana = getKibanaInfoForStats(server, kbnServer);

x-pack/test/api_integration/apis/xpack_main/settings/settings.js

@@ -35,6 +35,7 @@ export default function ({ getService }) {
         expect(body.settings.kibana.transport_address.length > 0).to.eql(true);
         expect(body.settings.kibana.version.length > 0).to.eql(true);
         expect(body.settings.kibana.status.length > 0).to.eql(true);
+        expect(body.settings.xpack.default_admin_email).to.eql(null);
       });
     });
   });