@Override
  public Set<String> getApplicableServices() {
    return Collections.emptySet();
  }
Gets the set of services that this check is associated with. If the check
is not associated with a particular service, then this should be an empty
set.

@return a set of services which will determine whether this check is
        applicable.
ambari-server/src/main/java/org/apache/ambari/server/checks/ClusterCheck.java