code: public String generateInstanceId () throws SchedulerException
    {
      String property = System.getProperty (getSystemPropertyName ());
      if (property == null)
        throw new SchedulerException ("No value for '" +
                                      SYSTEM_PROPERTY +
                                      "' system property found, please configure your environment accordingly!");
  
      if (getPrepend () != null)
        property = getPrepend () + property;
      if (getPostpend () != null)
        property = property + getPostpend ();
  
      return property;
    }
docs: Returns the cluster wide value for this scheduler instance's id, based on a
  system property
  
  @return the value of the system property named by the value of
  {@link #getSystemPropertyName()} - which defaults to
  {@link #SYSTEM_PROPERTY}.
  @throws SchedulerException
  Shouldn't a value be found