public function setAccessControlRequestHeaders(array $accessControlRequestHeaders)
    {
        // Validate all array elements are strings
        foreach ($accessControlRequestHeaders as $h) {
            if (is_string($h) === false) {
                throw new InvalidArgumentException(
                    'An element in array "accessControlRequestHeaders" is not a string'
                );
            }
        }

        $this->accessControlRequestHeaders = $accessControlRequestHeaders;

        return $this;
    }