private synchronized VersionDefinitionResourceProvider getVersionDefinitionResourceProvider() {
    if (versionDefinitionResourceProvider == null) {
      versionDefinitionResourceProvider = (VersionDefinitionResourceProvider) ClusterControllerHelper.
          getClusterController().ensureResourceProvider(Resource.Type.VersionDefinition);
    }
    return versionDefinitionResourceProvider;

  }
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