Different axis tick label interval than gridline interval

[antimatter84]

In my chart, I have a NumberAxis ranging from 40 to 220. By default or explicitly set with

numberAxis.setTickUnit(new NumberTickUnit(10));

I have horizontal grid lines in a 10 unit interval. Labels are shown as well as 40, 50, 60, etc.

How do I keep the 10 unit interval for the grid lines, but set a 20 unit interval for the number labels -> 40, 60, 80, ... ?