code: public Subscription changeOfferKeepCaptureDateNoRefund( String subscription, Offer offer ) {
      return changeOfferKeepCaptureDateNoRefund( new Subscription( subscription ), offer );
    }
docs: Change the offer of a subscription.<br>
  <br>
  the plan will be changed immediately. The next_capture_at date will remain unchanged. No refund will be given<br>
  <strong>IMPORTANT</strong><br>
  Permitted up only until one day (24 hours) before the next charge date.<br>
  
  @param subscription the subscription
  @param offer the new offer
  @return the updated subscription