public function setResourceIdentifier($resourceIdentifier)
    {
        if (is_string($resourceIdentifier) === false) {
            $msg = "The resourceIdentifier argument must be a string.";
            throw new InvalidArgumentException($msg);
        } elseif ($resourceIdentifier === '') {
            $msg = "The resourceIdentifier argument must be a non-empty string.";
            throw new InvalidArgumentException($msg);
        } else {
            $this->resourceIdentifier = $resourceIdentifier;
        }
    }