private void injectKeytab(ExecutionCommand ec, String command, String targetHost,
                            @Nullable Map<String, DesiredConfig> desiredConfigs) throws AmbariException {
    KerberosCommandParameterProcessor processor = KerberosCommandParameterProcessor.getInstance(command, clusters, ec, kerberosKeytabController);
    if (processor != null) {
      ec.setKerberosCommandParams(processor.process(targetHost, desiredConfigs));
    }
  }
Insert Kerberos keytab details into the ExecutionCommand for the SET_KEYTAB custom command if
any keytab details and associated data exists for the target host.

@param ec the ExecutionCommand to update
@param command a name of the relevant keytab command
@param targetHost a name of the host the relevant command is destined for
@param desiredConfigs desired config map
@throws AmbariException
ambari-server/src/main/java/org/apache/ambari/server/events/publishers/AgentCommandsPublisher.java