mulesoft/mule-module-varnish — pull request #2 by riccardonieto (2014-07-03 13:47:09+00:00)
Title:  Ban command is not working in Varnish release 4.0 #1 

I have added support for Varnish pre release 3 (included) and post one, because ban string command has changed in version 4
https://www.varnish-cache.org/docs/4.0/users-guide/purging.html