/**
* Checks if a string is (null) or contains whitespaces only.
*
* @param string $str The string to check.
* @param string $character_mask The custom list of whitespace characters to use.
*
* @return bool Is (null) / empty or not.
*/
public static final function isNullOrWhitespace($str, $character_mask = null) : bool
{
if (null === $str) {
return true;
}
if (!$str instanceof IString) {
$str = new self($str);
}
return $str->isWhitespace($character_mask);
}
