Strange return of ListGrid.isExpanded

Hello,

I am using SmartClient/SmartGWT Framework (SNAPSHOT_v9.1d_2013-12-30/Pro Deployment 2013-12-30).

The method
java.lang.Boolean isExpanded(ListGridRecord record)
does not return Boolean(false) but NULL if the record is not expanded.

Just a remark since according to the doc I did not expect this return value.
Andreas