@GET @ApiIgnore // until documented
  @Produces("text/plain")
  public Response getUpgrades( @Context HttpHeaders headers,
      @Context UriInfo ui) {
    return handleRequest(headers, null, ui, Request.Type.GET,
        createResourceInstance(null));
  }
Constructor.

@param clusterName the cluster name (not {@code null}).
ambari-server/src/main/java/org/apache/ambari/server/api/services/UpgradeService.java