title: Optaplanner: Extend vehiclerouting example to include secure transport
body: <p>I am want to add a simple boolean value to each vehicle that indicates if the vehicle is secure, then for each customer a similar boolean to indicate that the customer requires a secure vehicle. </p>
  
  <p>I have got as far as working out I need to:</p>
  
  <ul>
  <li>extend the domain objects for Vehicle and Customer to reflect these. </li>
  <li>extend the input XML to have at least one secure Vehicle and one Customer requiring a secure collection.</li>
  <li>extend the vehicleRoutingScoreRules.drl to add a new rule "secure" with a hard constraint. </li>
  </ul>
  
  <p>This is a little pathetic - but I am pushed for time and the drools manual is massive and I cannot figure out the syntax for what I think is a simple rule. Could some kind soul give me a starter here please.  </p>