private void checkArgument(boolean argument, String msg, Object... args) {
        if (!argument) {
            throw new IllegalArgumentException(String.format(msg, args));
        }
    }
private void checkArgument ( boolean argument , String msg , Object ... args ) { if ( ! argument ) { throw new IllegalArgumentException ( String . format ( msg , args ) ) ; } }
copy of Guava to avoid including Guava in this core library