public static UUID getUniqueId(String username) {
        return UUID.nameUUIDFromBytes(("OfflinePlayer:" + username).getBytes());
    }
Gets the {@link UUID} given to a player with the
given username on an offline mode server.

@param username the name of the player
@return the uuid
helper/src/main/java/me/lucko/helper/profiles/OfflineModeProfiles.java