I want to get fully away from blocking methods and instead make the
user/player/prisoner/whatever wait to get an answer while we retrieve
the uuid information asynchronously.
time from a prisoner's sentence.
This command could be useful for commandblocks or something else, as it
does not need a player context. This closes Bukkit Dev Ticket:
http://dev.bukkit.org/bukkit-plugins/jail/tickets/432/