탭을 눌렀을때 명령어가 자동완성 되게 하고싶어 아래와 같은 코드를 짰지만 실행되지 않습니다.

package upload18.quickemote;

import org.bukkit.command.Command;
import org.bukkit.command.CommandSender;
import org.bukkit.command.TabCompleter;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.util.ArrayList;
import java.util.List;
import java.util.Locale;

public class TabCom implements TabCompleter {

    List<String> arguments = new ArrayList<String>();
    @Override
    public @Nullable List<String> onTabComplete(@NotNull CommandSender sender, @NotNull Command command, @NotNull String label, @NotNull String[] args) {
        if (arguments.isEmpty()) {
            arguments.add("subu");
            arguments.add("died");
            arguments.add("hand");
            arguments.add("boom");
        }

        List<String> result = new ArrayList<String>();
        if (args.length == 1) {
            for (String a : arguments) {
                if (a.toLowerCase().startsWith(args[0].toLowerCase()))
                    result.add(a);
            }
        }

        return null;
    }
}