First, let me recognize that this type of issue is the next order of convenience :) I know there are still more fundamental things to do more for the first pass, but let me write it up anyway.
To add config like this:
<quickStartSecurity userName="abc" userPassword="123"></quickStartSecurity>
I need to do three separate completions. One for the element itself, then one for each attribute.
But I never use this element without supplying these attributes. I'm almost surprised they're not required in XSD.
I'd find it more useful for the completion to start more like:
<quickStartSecurity userName="admin" userPassword="pwd"/>
If this isn't easy to do with Lemminx's XSD-based completion, would it be possible to do more as a "snippet" ?