It is possible to use font-awesome icons if you like. You need to include the Font Awesome CSS in your application. That will enable you to use the icon classes to use those icons.
Check out the demo
Bring your own icons
It is also possible to use your own SVG icons if you like, you can customize this by using the SASS files.
Recent Font Awesome support
The contextmenu supports the new Font Awesome by including the correct font-awesome CSS and adding the new classes as icon for a menu item. When using for example
fas fa-beer it will crete the
i tag for the icon in the menu and adjust CSS accordingly.