import of data in drop-down lists fails due to add_dropdonw parameter absent in itsm 1.5.1

[Priif]

I'm using istm-ng 1.5.1 along with fields and datainjection plugins.
I had to comment part of lines 579 & 585 from file commoninjectionlib.class in plugin/datainjection/inc/
$this->rights['add_dropdown'])
this statement is always false because the add_dropdown parameter is not present in itsm-ng 1.5.1

Is it safe to do so ?
Are you going to update itsm-ng to add the add_dropdown parameter soon ?