title: I am creating highchart with wicket. I am getting issue in multiple x-axis
body: <p>I am creating highchart with wicket. I am getting issue in multiple x-axis. 
  So my requirement is </p>
  
  <p>I've one Y-axis which will show the values.
  I have two x-axis.<br>
  so let's assume the data is in format </p>
  
  <p>| Period     |    Name     |     Data     |</p>
  
  <p>|:-----------|------------:|:------------</p>
  
  <p>| 08/2015    |        A    |     10<br>
  | 08/2015    |        B    |     15<br>
  | 08/2015    |        A    |     17<br>
  | 09/2015    |        B    |     19<br>
  | 09/2015    |        C    |     20<br>
  | 10/2015    |        B    |     21<br>
  | 10/2015    |        C    |     23        </p>
  
  <p>I am able to create simple Name-Data bar chart having name as X-axis and passing all the values of name as categories and data in Y-axis. 
  But now I have to create a bar chart with 2 X-axis. other X axis will just mark the start and end of period in first X-axis. So my bar chart will have another axis marking the period the x-axis data belongs to. </p>