private synchronized HostResourceProvider getHostResourceProvider() {
    if (hostResourceProvider == null) {
      hostResourceProvider = (HostResourceProvider)
          ClusterControllerHelper.getClusterController().ensureResourceProvider(Resource.Type.Host);

    }
    return hostResourceProvider;
  }
Gets an instance of {@link ConfigHelper} for classes which are not
dependency injected.

@return a {@link ConfigHelper} instance.
ambari-server/src/main/java/org/apache/ambari/server/topology/AmbariContext.java