When we originally plan to do this, we consider about `/logstream?tail=n` and the result is text based streaming last n events.  Is there a reason to introduce a new one-off path for this?  Also why coerces them into json format?  This restricts us to request/reply buffered pattern as opposed to pure streaming.  We should try to use the raw text format (save server CPU/memory) and do conversion on client side.