Comment 5 for bug 1809238

Reviewed: https://review.openstack.org/626561
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=e8b7e768a2545621ee98511b8dd271c5117f76bd
Submitter: Zuul
Branch: master

commit e8b7e768a2545621ee98511b8dd271c5117f76bd
Author: LIU Yulong <email address hidden>
Date: Mon Dec 17 11:38:20 2018 +0800

    Add dependency for service plugin

    Adds a required list 'required_service_plugins' to each service plugin,
    then we can initialize the service plugin with required dependency.
    And also adds the 'router' plugin to port forwarding service plugin
    required list.

    Closes-Bug: #1809238
    Change-Id: I53fdaee0cd96a5315a7abc39799657d613eb3a2e