Add class to Drupal Bootstrap li tags subtheme

I have a bootstrap subtheme in Drupal and need template modifications to create specific classes for primary and secondary menu in <li> tags. Convert this: <ul class="menu nav navbar-nav"> <li class="first leaf"></li> <li class="leaf"></li> <li class="last leaf"></li> </ul> To this: <ul class="menu nav navbar-nav"> <li class="first leaf myclassmenuname1"></li> <li class="leaf myclassmenuname2"></li> <li class="last leaf myclassmenuname3"></li> </ul> This is an small project, you will receive access to a sandbox copy of my website (so no need to reinstall in your server). You will provide me the modified files and the directory where have to be saved. You must know how Drupal Bootstrap subtheme structure works.