The new bot api now supports slash commands using the default command methods. Make sure your command has a description, and you update your command events.

Some things to note;
Commands new run method
run( @NotNull SlashCommandEvent event)
You can not remove a message from a command.
You MUST use event.getHook().sendMessage().queue() to send a message now.
Double check for null pointers when it asks!

Hope you enjoy the update.