src/Collection/Type.php
public function getOrderBy()
    {
        if ($this->order_by === false) {
            $this->order_by = $this->pool->getEscapedTypeOrderBy($this->getRegisteredType());
        }

        return $this->order_by;
    }
public function getOrderBy()
    {
        if ($this->order_by === false) {
            $this->order_by = $this->pool->getEscapedTypeOrderBy($this->getRegisteredType());
        }

        return $this->order_by;
    }
Return order by.

@return string|null