Issues ACL request on the provided uri, or, in case it's null, on the URI defined in
associated Source.
| this | |
| uri |
URI to issue the request for, or null to read from Source |
| xml |
the request itself, as an XmlDocument, the root element should be DAV:acl |
| cancellable |
optional Cancellable object, or null |
|
Whether succeeded. |