The BooleanArgument class represents boolean values true and false.

String[] configKeys = getConfig().getKeys(true).toArray(new String[getConfig().getKeys(true).size()]);

LinkedHashMap<String, Argument> arguments = new LinkedHashMap<>();
arguments.put("config-key", new TextArgument().overrideSuggestions(configKeys));
arguments.put("value", new BooleanArgument());

CommandAPI.getInstance().register("editconfig", arguments, (sender, args) -> {
    getConfig().set((String) args[0], (boolean) args[1]);
});

Numbers are represented using the designated number classes:

Each numerical argument can have ranges applied to them, which restricts the user to only entering numbers from within a certain range. This is done using the constructor, and the range specified:

Each range is inclusive, so it includes the number given to it.