title: REST API style for tree structure
body: <p>I have items in tree structure.  Each <code>Item</code> has <code>Id</code> and <code>ParentId</code>.</p>
  
  <p>To get <code>Item</code> by <code>Id</code> I use <code>items/:id</code></p>
  
  <p>What is the best way to create endpoint for <code>GetItemsByParentId(parentId)</code> method?</p>