iconMove and iconRemove parameters seems to be ignored

[goiaba]

First of all, thank you for having the time to make this widget available to all of us.

Well, I'm trying to use iconMove and iconRemove parameters do define my own icons in bootstrap-duallistbox but they seem to be completely ignored.

Looking at the js source code I noticed these options do not exist in v4 (default) branch.

Could someone help me to understand what am I doing wrong?

Thanks in advance.