@Path("{upgradeItemId}/tasks")
  public TaskService getTasks(
      @Context HttpHeaders headers,
      @Context UriInfo ui,
      @PathParam("upgradeItemId") Long id) {
    return new TaskService(m_clusterName, m_upgradeId, id.toString());
  }
Handles:
PUT /clusters/{clusterId}/upgrades/{upgradeId}/upgrade_groups/{upgradeGroupId}/upgrade_items/{upgradeItemId}

Change state of existing upgrade item.

@param body     http body
@param headers  http headers
@param ui       uri info
@param id       the upgrade item id

@return information regarding the created services
ambari-server/src/main/java/org/apache/ambari/server/api/services/UpgradeItemService.java