public function setForcedVariation($experimentKey, $userId, $variationKey)
    {
        if (!$this->validateInputs(
            [
                self::EXPERIMENT_KEY =>$experimentKey,
                self::USER_ID => $userId
            ]
        )) {
            return false;
        }
        return $this->_config->setForcedVariation($experimentKey, $userId, $variationKey);
    }