SPIGOT-5531: Fix --universe option

nms-patches/MinecraftServer.patch

@@ -597,7 +597,7 @@
              DispenserRegistry.init();
              DispenserRegistry.c();
 -            String s = (String) optionset.valueOf(optionspec8);
-+            String s = (String) optionset.valueOf("universe"); // CraftBukkit
++            File s = (File) optionset.valueOf("universe"); // CraftBukkit
              YggdrasilAuthenticationService yggdrasilauthenticationservice = new YggdrasilAuthenticationService(Proxy.NO_PROXY, UUID.randomUUID().toString());
              MinecraftSessionService minecraftsessionservice = yggdrasilauthenticationservice.createMinecraftSessionService();
              GameProfileRepository gameprofilerepository = yggdrasilauthenticationservice.createProfileRepository();