protected function setConstants()
    {
        $this->parsedHeaders = $this->headers($this->filePath, $this->headers);

        $domainVar = $this->parsedHeaders['domain_var'] ?? 'PLUGIN_TD';
        $domainVar = strtoupper($domainVar);
        $textDomain = $this->parsedHeaders['text_domain'] ?? 'plugin-textdomain';

        if (! defined($domainVar)) {
            define($domainVar, $textDomain);
        }
    }