Return task as nodeId:taskId

plugins/reindex/src/main/java/org/elasticsearch/plugin/reindex/AbstractBaseReindexRestHandler.java

@@ -73,10 +73,7 @@ public abstract class AbstractBaseReindexRestHandler<Request extends ActionReque
     private void sendTask(RestChannel channel, Task task) throws IOException {
         XContentBuilder builder = channel.newBuilder();
         builder.startObject();
-        builder.startObject("task");
-        builder.field("node", clusterService.localNode().getId());
-        builder.field("id", task.getId());
-        builder.endObject();
+        builder.field("task", clusterService.localNode().getId() + ":" + task.getId());
         builder.endObject();
         channel.sendResponse(new BytesRestResponse(RestStatus.OK, builder));
     }

plugins/reindex/src/test/resources/rest-api-spec/test/reindex/10_basic.yaml

@@ -22,6 +22,7 @@
   - match: {batches: 1}
   - match: {failures: []}
   - is_true: took
+  - is_false: task
 
 ---
 "Response format for updated":
@@ -53,6 +54,7 @@
   - match: {batches: 1}
   - match: {failures: []}
   - is_true: took
+  - is_false: task
 
 ---
 "wait_for_completion=false":
@@ -73,8 +75,7 @@
             index: source
           dest:
             index: dest
-  - is_true: task.node
-  - is_true: task.id
+  - match: {task: '/.+:\d+/'}
   - is_false: updated
   - is_false: version_conflicts
   - is_false: batches

plugins/reindex/src/test/resources/rest-api-spec/test/update-by-query/10_basic.yaml

@@ -18,7 +18,8 @@
   - match: {failures: []}
   - match: {noops: 0}
   - is_true: took
-  - is_false: created # This shouldn't be included in the response
+  - is_false: created # Update by query can't create
+  - is_false: task
 
 ---
 "wait_for_completion=false":
@@ -35,8 +36,7 @@
       update-by-query:
         wait_for_completion: false
         index: test
-  - is_true: task.node
-  - is_true: task.id
+  - match: {task: '/.+:\d+/'}
   - is_false: updated
   - is_false: version_conflicts
   - is_false: batches