title: Adding numbering to documents in Xpages
body: <p>I needs some tips on this one, since I couldn't find anything on this, though it's probably pretty simple to do, but I can't think of a way.
  Ok, so I need a hidden field which will automatically compute so called id numbers for every document, the numbers must start from 00001 and forward and must never ever repeat. For instance i create a document with numberId = 00001 and another document which creates numberId = 00002, if I ever delete the first or second document, the third created document should have numberId = 00003. No matter how many documents get deleted, the next document created should get the latest numberId and add 1 to it.</p>
  
  <p>I hope I was clear about what I need here. I need an advice or a tip on how would I achieve this.</p>
  
  <p>Also, I can't use @Unique.</p>