Fix broken TaskInfo.toString()

Related to #22387

core/src/main/java/org/elasticsearch/action/admin/cluster/node/tasks/list/ListTasksResponse.java

@@ -161,8 +161,9 @@ public class ListTasksResponse extends BaseTasksResponse implements ToXContentOb
             }
             builder.startObject("tasks");
             for(TaskInfo task : entry.getValue()) {
-                builder.field(task.getTaskId().toString());
+                builder.startObject(task.getTaskId().toString());
                 task.toXContent(builder, params);
+                builder.endObject();
             }
             builder.endObject();
             builder.endObject();

core/src/main/java/org/elasticsearch/action/admin/cluster/node/tasks/list/TaskGroup.java

@@ -81,7 +81,7 @@ public class TaskGroup implements ToXContent {
     @Override
     public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
         builder.startObject();
-        task.innerToXContent(builder, params);
+        task.toXContent(builder, params);
         if (childTasks.isEmpty() == false) {
             builder.startArray("children");
             for (TaskGroup taskGroup : childTasks) {

core/src/main/java/org/elasticsearch/tasks/TaskInfo.java

@@ -163,12 +163,6 @@ public final class TaskInfo implements Writeable, ToXContent {
 
     @Override
     public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
-        builder.startObject();
-        innerToXContent(builder, params);
-        return builder.endObject();
-    }
-
-    public XContentBuilder innerToXContent(XContentBuilder builder, Params params) throws IOException {
         builder.field("node", taskId.getNodeId());
         builder.field("id", taskId.getId());
         builder.field("type", type);

core/src/main/java/org/elasticsearch/tasks/TaskResult.java

@@ -160,7 +160,9 @@ public final class TaskResult implements Writeable, ToXContent {
 
     public XContentBuilder innerToXContent(XContentBuilder builder, Params params) throws IOException {
         builder.field("completed", completed);
-        builder.field("task", task);
+        builder.startObject("task");
+        task.toXContent(builder, params);
+        builder.endObject();
         if (error != null) {
             XContentHelper.writeRawField("error", error, builder, params);
         }

core/src/test/java/org/elasticsearch/action/admin/cluster/node/tasks/TaskTests.java

@@ -0,0 +1,51 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.elasticsearch.action.admin.cluster.node.tasks;
+
+import org.elasticsearch.common.bytes.BytesArray;
+import org.elasticsearch.common.xcontent.XContentHelper;
+import org.elasticsearch.tasks.TaskId;
+import org.elasticsearch.tasks.TaskInfo;
+import org.elasticsearch.test.ESTestCase;
+
+import java.nio.charset.StandardCharsets;
+import java.util.Map;
+
+public class TaskTests extends ESTestCase {
+
+    public void testTaskInfoToString() {
+        String nodeId = randomAsciiOfLength(10);
+        long taskId = randomIntBetween(0, 100000);
+        long startTime = randomNonNegativeLong();
+        long runningTime = randomNonNegativeLong();
+        boolean cancellable = randomBoolean();
+        TaskInfo taskInfo = new TaskInfo(new TaskId(nodeId, taskId), "test_type",
+            "test_action", "test_description", null, startTime, runningTime, cancellable, TaskId.EMPTY_TASK_ID);
+        String taskInfoString = taskInfo.toString();
+        Map<String, Object> map = XContentHelper.convertToMap(new BytesArray(taskInfoString.getBytes(StandardCharsets.UTF_8)), true).v2();
+        assertEquals(((Number)map.get("id")).longValue(), taskId);
+        assertEquals(map.get("type"), "test_type");
+        assertEquals(map.get("action"), "test_action");
+        assertEquals(map.get("description"), "test_description");
+        assertEquals(((Number)map.get("start_time_in_millis")).longValue(), startTime);
+        assertEquals(((Number)map.get("running_time_in_nanos")).longValue(), runningTime);
+        assertEquals(map.get("cancellable"), cancellable);
+    }
+
+}