-- is back.SPIGOT-1569
After calling Bukkit.createMap(World) [which returns a MapView], calling MapView.getId() on the returned object will always return a value of zero.
There was a demo plugin that was attached to 1569 that I have reattached here for convenience. I have repasted the decompiled plugin code here as the paste linked in 1569 no longer exists. The only editing I did was for formatting.
The latest.log shows the output of the demo plugin, which was the only plugin running.