code: protected void submitMachineConfiguratorUseWithCaution( String machineId, MachineConfigurator configurator ) {
  		if( configurator != null ) {
  			this.logger.fine( "Configuring machine '" + machineId + "' (" + configurator.getClass().getSimpleName() + ")." );
  			this.machineIdToConfigurators.put( machineId, configurator );
  		}
  	}
docs: Submits a machine configurator.
  <p>
  Most of the subclasses will never use this method. It is already invoked from
  the {@link #configureMachine(TargetHandlerParameters, String, Instance)} method.
  </p>
  <p>
  Most of target handlers only have long-running configurations but short
  terminations. In some cases though, terminating a machine might take time and using
  a configurator might be better. In such situations, a sub-class may invoke this method
  to run such a configurator. As a reminder, the target handler is in charge of generating a machine ID.
  And any submitted job can be cancelled with {@link #cancelMachineConfigurator(String)}.
  </p>
  
  @param machineId a machine ID (not null)
  @param configurator a configurator (will not be added if null)