protected function createAppXmlFile()
    {
        $appName = self::APP_NAME;
        $appXmlFileContents = <<<EOD
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<Properties xmlns="http://schemas.openxmlformats.org/officeDocument/2006/extended-properties">
    <Application>$appName</Application>
    <TotalTime>0</TotalTime>
</Properties>
EOD;

        $this->createFileWithContents($this->docPropsFolder, self::APP_XML_FILE_NAME, $appXmlFileContents);

        return $this;
    }