No response on commands without arguments

[xxDark]

commandDispatcher.register(Commands.literal(".ping") .executes(c -> { c.getSource() .getChannel().sendMessage("Pong!"); return 1; }) );

And, using this code:
CommandNode<DiscordCommandSource> commandNode = Iterables.getLast(results.getContext().getNodes().keySet()); Map<CommandNode<DiscordCommandSource>, String> map = commandDispatcher.getSmartUsage(commandNode, s.getSource());
It does not return an information about commands without arguments. Am I doing something wrong?