Comment 12 for bug 1763824

Reviewed: https://review.openstack.org/561354
Committed: https://git.openstack.org/cgit/openstack/keystone/commit/?id=22af1d9f35c86e9c5bca288c2996be5c19e3cd61
Submitter: Zuul
Branch: stable/pike

commit 22af1d9f35c86e9c5bca288c2996be5c19e3cd61
Author: Morgan Fainberg <email address hidden>
Date: Fri Apr 13 13:34:31 2018 -0700

    Fix json schema nullable to add None to ENUM

    The JSON Schema validation implementation of nullable(), which makes
    values possible to be null was not adding None to the enum if it exists.
    This causes validation to fail on ``None`` especially in the case of
    keystone's boolean parameter_type implementation. ``nullable()`` now
    adds ``None`` to the enum if the enum exists.

    Closes-Bug: #1763824
    Change-Id: I176fa90df63049661413c445554dba9b7d87272a
    (cherry picked from commit 78adf4b40fb88e371101ed065ac1d15063d8d86e)