title: How to get page content height using pdfbox
body: <p>Is this possible to get the height of the page content using pdfbox?
  I think I tried everything but each (PDRectangle) returns full height of the page: 842.
  First I thought that this is because the page number place at the bottom of the page, but when I opened pdf in Illustrator, the whole content is inside compound element, and isn't extended to the whole page height. So if illustrator can see it as separate element and calculate its height, I guess this should also be possible in pdfbox.</p>
  
  <p>Sample page:</p>
  
  <p><img src="https://i.stack.imgur.com/n3RYO.png" alt="enter image description here"></p>