Retrieve Functional Priviledges

Normally I use the “FunctionalPriviledgeProvider” to get the functional priviledges. However even with this we donot get the list of functional priviledges but we can only verify usingthe (isGranted) method.

Is there a way to access the functional priviledges of a specific Role ??? using MWS API ?
I want to access all the values available in the Permissions Managmenet Page.

Help needed!!