protected function validateFormatters()
    {
        foreach ($this->formatters as $fe) {
            if ($fe->getType() == '') {
                throw new BuildException('Formatter missing required "type" attribute.');
            }

            if ($fe->getUsefile() && $fe->getOutfile() === null) {
                throw new BuildException('Formatter requires "outfile" attribute when "useFile" is true.');
            }
        }
    }