Address comments from blueprint patches
This is a follow-up patch addressing the following comments:
- add missing destroy-method: https://git.opendaylight.org/gerrit/#/c/45750/
- refactor class name, remove useless param and got back to simple map/set
as there is no obvious need to have them concurrent: https://git.opendaylight.org/gerrit/#/c/45608/
- add TODO back: https://git.opendaylight.org/gerrit/#/c/45631/
Change-Id: Ie4648aa520717effbfe367de62a2fb7d6b1d3505
Signed-off-by: Alexis de Talhouët <adetalhouet@inocybe.com>