title: How to handle variable number of process variables in Camunda
body: <p>I'm new to Camunda and didn't find any tutorial or reference explaining how to achieve the following:</p>
  
  <p>When starting a process I want the user to add as many items as he likes to an invoice. On the next user task all those items and their quantity should be printed to somebody approving the data.</p>
  
  <p>I don't understand yet how to get this 1:n relationship between a process and its variables working. Do I need to start subprocesses for each item? Or do I have to use a custom Java object? If so, how can I map form elements to such an object from within the Tasklist?</p>