Query if a room alias should exist on the application service.
GET {{baseUrl}}/rooms/:roomAlias
This endpoint is invoked by the homeserver on an application service to query
the existence of a given room alias. The homeserver will only query room
aliases inside the application service's aliases
namespace. The
homeserver will send this request when it receives a request to join a
room alias within the application service's namespace.
RESPONSES
status: OK
{}