Only expand ExpandableDrawerItem when click on arrow

[mvalois]

As in https://github.com/mikepenz/MaterialDrawer/issues/1158#issuecomment-207995248, I would like to expand/collapse ExpandableDrawerItem only when clicking on arrow, and keep PrimaryDrawerItem's default action when clicking elsewhere (for instance the label).

However, the proposed code is in Java while I would like it in Kotlin. Is there any lead to achieve such behavior? Thanks you :)