public static void addAffectedCluster(Cluster cluster) {
    if (operationsRetryAttempts > 0 ) {
      affectedClusters.get().add(cluster);
    }
  }
Provides utility methods to support operations retry
TODO injection as Guice singleon, static for now to avoid major modifications
ambari-server/src/main/java/org/apache/ambari/server/utils/RetryHelper.java