title: CVRPTW with Precedences amd vehicle failure in OptaPlanner
body: <p>I have a problem and it is really hard for me to manage it. I want to use OptaPlanner to solve a CVRPTW with Precedences and vehicle failures. What I have done so far is to get the standard example and solve it in the GUI, and then save the results. Than I modified the .xml file in python, to manually delete a vehicle and free the customers. I know the right way is to make a ProblemFact, but I don't have a clue how to do this. I saw some answers, but I would need more help or an example of how it is done. </p>
  
  <p>The second thing is, how I could model precedences. So customer 'A' has to come before customer 'B'. (The only example is within another problem called Project Job Scheduling)</p>
  
  <p>Thank you very much!</p>