code: private void onProbationHit(Node node) {
      admittor.record(node.key);
  
      node.remove();
      node.status = Status.PROTECTED;
      node.appendToTail(headProtected);
  
      sizeProtected++;
      if (sizeProtected > maxProtected) {
        Node demote = headProtected.next;
        demote.remove();
        demote.status = Status.PROBATION;
        demote.appendToTail(headProbation);
        sizeProtected--;
      }
    }
docs: Promotes the entry to the protected region's MRU position, demoting an entry if necessary.