Converts value into string or returns default when value is None.

        :param value: the value to convert.

        :param default_value: the default value.

        :return: string value or default when value is null.

def to_string_with_default(value, default_value):
        """
        Converts value into string or returns default when value is None.

        :param value: the value to convert.

        :param default_value: the default value.

        :return: string value or default when value is null.
        """
        result = StringConverter.to_nullable_string(value)
        return result if result != None else default_value