@Override
                public void run() {
                  try {
                    prepareIdentities.processServiceComponentHosts(cluster, kerberosDescriptor, schToProcess, null, dataDirectory, configurations, kerberosConfigurations, includeAmbariIdentity, propertiesToIgnore);
                  } catch (AmbariException e) {
                    throw new RuntimeException(e);
                  }
                }
Upgrades kerberos related data.
Also creates keytabs and principals database records. This happens via code in PrepareKerberosIdentitiesServerAction,
so code reused and all changes will be reflected in upgrade.

@throws AmbariException
ambari-server/src/main/java/org/apache/ambari/server/upgrade/UpgradeCatalog270.java