title: MPAndroidChart with null values
body: <p>I'm using the <a href="https://github.com/PhilJay/MPAndroidChart" rel="nofollow noreferrer">MPAndroidChart</a> and am really enjoying it.</p>
  
  <p>A 'little' need I have is that I can put null values to the 'entrys'. I'm monitoring the apache conections on servers of my system, and I would to see if they is down (where I put the null value) or if they just no conections (0).</p>
  
  <p>I tried, but the Entry class don't accept 'null' as value showing the message: 'The constructor Entry(null, int) is undefined'</p>
  
  <p>Thanks!</p>