SpigotCore_Main/src/de/steamwar/command/SWCommand.java

@@ -60,13 +60,14 @@ public abstract class SWCommand {
 
             @Override
             public List<String> tabComplete(CommandSender sender, String alias, String[] args) throws IllegalArgumentException {
+                String string = args[args.length - 1].toLowerCase();
                 return commandList.stream()
                         .map(s -> s.tabComplete(sender, args))
                         .filter(Objects::nonNull)
                         .flatMap(Collection::stream)
                         .filter(s -> !s.isEmpty())
                         .filter(s -> !s.isBlank())
-                        .filter(s -> s.toLowerCase().startsWith(args[args.length - 1].toLowerCase()))
+                        .filter(s -> s.toLowerCase().startsWith(string))
                         .collect(Collectors.toList());
             }
         };