Sometime (PPPoE server is one of em) ona simple defaultValue in the XML is not enough - several are set.

In order to support a list of defaultValues you can now simply list them as a whitespace separated string.

Example:
<defaultValue>pap chap mschap mschap-v2</defaultValue>

will generate a list ['pap', 'chap', 'mschap', 'mschap-v2'] when retrieved by vyos.xml.defaults()