private void uninstallService(String service, List<Component> components) throws KerberosMissingAdminCredentialsException {
    kerberosIdentityCleaner.serviceRemoved(new ServiceRemovedEvent(CLUSTER_ID, "any", "any", service, components));
  }
Ensures that when an upgrade is in progress, new requests are not created
to remove identities since it would interfere with the long running
upgrade.

@throws Exception
ambari-server/src/test/java/org/apache/ambari/server/controller/utilities/KerberosIdentityCleanerTest.java