slack_incoming: Strengthen types using WildValue.
slack_incoming: Strengthen types using WildValue.

rht/zulip,andersk/zulip,andersk/zulip,rht/zulip,zulip/zulip,rht/zulip,andersk/zulip,rht/zulip,zulip/zulip,andersk/zulip,andersk/zulip,zulip/zulip,zulip/zulip,zulip/zulip,rht/zulip,zulip/zulip,andersk/zulip,zulip/zulip,rht/zulip,andersk/zulip,rht/zulip