message: Increase Christmas-challenge difficulty to 4
  Rationale: This is not solvable through the UI
  any longer but requires direct REST-API
  interaction with the shopping basket, making it
  more difficult.
diff: name: 'Christmas Special'
  category: 'Injection'
  description: 'Order the Christmas special offer of 2014.'
  - difficulty: 3
  + difficulty: 4
  hint: 'Find out how the application handles unavailable products and try to find a loophole.'
  hintUrl: 'https://bkimminich.gitbooks.io/pwning-owasp-juice-shop/content/part2/injection.html#order-the-christmas-special-offer-of-2014'
  key: christmasSpecialChallenge
  