public void setIcon(Icon newIcon) {
		if (icon == newIcon) {
			return;
		}
		ToolBarData oldData = new ToolBarData(icon, toolBarGroup, toolBarSubGroup);
		icon = DockingUtils.scaleIconAsNeeded(newIcon);
		firePropertyChanged(oldData);
	}
Returns the subgroup string.  This string is used to sort items within a 
{@link #getToolBarGroup() toolbar group}.  This value is not required.  If not specified, 
then the value will effectively place this item at the end of its specified group.
@return the subgroup
Ghidra/Framework/Docking/src/main/java/docking/action/ToolBarData.java