public final function setEntityClass($str_class)
    {
        if(class_exists($str_class)) {
            if(is_a($str_class, '\\GDS\\Entity', TRUE)) {
                $this->str_entity_class = $str_class;
            } else {
                throw new \InvalidArgumentException('Cannot set an Entity class that does not extend "GDS\Entity": ' . $str_class);
            }
        } else {
            throw new \InvalidArgumentException('Cannot set missing Entity class: ' . $str_class);
        }
        return $this;
    }