the sort key "user" in event-list cannot work

[miaohb]

In the help of event-list, the sort key "user" is listed. However, it cannot work actually.

stack@tecs:/home/tecs$ openstack cluster event list -h
usage: openstack cluster event list [-h] [-f {csv,json,table,value,yaml}]
                                    [-c COLUMN] [--max-width <integer>]
                                    [--noindent]
                                    [--quote {all,minimal,none,nonnumeric}]
                                    [--filters <"key1=value1;key2=value2...">]
                                    [--limit <limit>] [--marker <id>]
                                    [--sort <key>[:<direction>]]
                                    [--global-project] [--full-id]

List events.

optional arguments:
  -h, --help show this help message and exit
  --filters <"key1=value1;key2=value2...">
                        Filter parameters to apply on returned events. This
                        can be specified multiple times, or once with
                        parameters separated by a semicolon. The valid filter
                        keys are: ['level', 'otype', 'oid' ,'cluster_id',
                        'oname', 'action']
  --limit <limit> Limit the number of events returned
  --marker <id> Only return events that appear after the given event
                        ID
  --sort <key>[:<direction>]
                        Sorting option which is a string containing a list of
                        keys separated by commas. Each key can be optionally
                        appended by a sort direction (:asc or :desc). The
                        valid sort keys are: ['timestamp', 'level', 'otype',
                        'oname', 'user', 'action', 'status']