public function setRequirements()
    {
        if (!isset($this->options['requirements']) || $this->options['requirements'] === null) {
            return $this;
        }

        $requirements = $this->options['requirements'];

        if (!is_array($requirements)) {
            $requirements = [$requirements];
        }

        foreach ($requirements as $constraint) {
            $this->requirements[] = $constraint;
        }

        unset($this->options['requirements']);

        return $this;
    }