Add annotation support

Author: haohanyang

src/datasource.ts

@@ -8,7 +8,7 @@ import {
   dateTime,
   LiveChannelScope,
   DataQueryResponse,
-  LoadingState,
+  LoadingState
 } from '@grafana/data';
 import { DataSourceWithBackend, getGrafanaLiveSrv, getTemplateSrv } from '@grafana/runtime';
 import {
@@ -75,6 +75,8 @@ export class DataSource extends DataSourceWithBackend<MongoQuery, MongoDataSourc
     };
   }
 
+  annotations = {}
+
   async metricFindQuery(query: VariableQuery, options?: LegacyMetricFindQueryOptions): Promise<MetricFindValue[]> {
     const request: DataQueryRequest<MongoQuery> = {
       requestId: 'variable-query-' + randomId(3),

src/plugin.json

@@ -7,6 +7,7 @@
   "id": "haohanyang-mongodb-datasource",
   "metrics": true,
   "backend": true,
+  "annotations": true,
   "executable": "gpx_mongodb_datasource",
   "info": {
     "description": "MongoDB integration and data source",