elasticsearch: Fix the _source parameter on mget

types/elasticsearch/elasticsearch-tests.ts

@@ -206,7 +206,8 @@ client.mget({
   index: 'myindex',
   type: 'mytype',
   body: {
-    ids: [1, 2, 3]
+    ids: [1, 2, 3],
+    _source: ['test']
   }
 }, (error, response) => {
   // ...

types/elasticsearch/index.d.ts

@@ -465,7 +465,7 @@ export interface MGetParams extends GenericParams {
     preference?: string;
     realtime?: boolean;
     refresh?: boolean;
-    source?: NameList;
+    _source?: NameList;
     _sourceExclude?: NameList;
     _sourceInclude?: NameList;
     index?: string;