@PUT @ApiIgnore // until documented
  @Path("{stageId}")
  @Produces("text/plain")
  public Response updateStages(String body, @Context HttpHeaders headers, @Context UriInfo ui,
                               @PathParam("stageId") String stageId) {
    return handleRequest(headers, body, ui, Request.Type.PUT, createStageResource(m_clusterName, m_requestId, stageId));
  }
Handles: PUT /clusters/{clusterId}/requests/{requestId}/stages/{stageId} or /requests/{requestId}/stages/{stageId}
Change state of existing stages.

@param body        http body
@param headers     http headers
@param ui          uri info
@return information regarding the created services
ambari-server/src/main/java/org/apache/ambari/server/api/services/StageService.java