src/Manipulation/JoinQuery.php
public function joinCondition()
    {
        if (!isset($this->joinCondition)) {
            $this->joinCondition = QueryFactory::createWhere($this->select);
        }

        return $this->joinCondition;
    }
public function joinCondition()
    {
        if (!isset($this->joinCondition)) {
            $this->joinCondition = QueryFactory::createWhere($this->select);
        }

        return $this->joinCondition;
    }
WHERE constrains used for the ON clause of a (LEFT/RIGHT/INNER/CROSS) JOIN.

@return Where