protected static function sanitize_attribute_value($str = '') {
		$str = wp_kses_no_null($str);

		// Decode all entities.
		$old_value = '';
		while ($old_value !== $str) {
			$old_value = $str;
			$str = wp_kses_decode_entities($str);
			$str = html_entity_decode($str, ENT_QUOTES, 'UTF-8');

			// And (full) trim while we're here.
			$str = preg_replace('/^\s+/u', '', $str);
			$str = preg_replace('/\s+$/u', '', $str);
		}

		return $str;
	}