highslide-software/highcharts.com — pull request #2194 by CodeCommander (2013-08-27 15:36:04+00:00)
Title: Treat hasNulls for dataGrouping as a counter instead of a boolean.

Implementation of feature request here:

http://uservoice.com/a/OheZi

This hasNulls can still be checked for "truthiness" but this gives the additional ability to judge how much of the data was null. (e.g. when > 50% of the points were null we can return null instead of averaging/summing)