public function addExpressionCondition($expression) {
        if(!isset($this->_subscription->subject)){
            $this->_subscription->subject = (object) [];
        }

        if(!isset($this->_subscription->subject->condition)){
            $this->_subscription->subject->condition = (object) [];
        }


        $this->_subscription->subject->condition->expression = $expression;
        return $this;
    }