(Its index.jelly does assume getDisplayName is available.)

fixing NPE introduced by change offline note feature
Thanks

no need to call toString() on the string
add comments

 - massaging exception handling
 - leaving a TODO for a possible future enhancement

@kohsuke suggests using '@' as separator between shortName & version, rather than ' ', in case we want to allow multiple owners in the future.

[FIXED JENKINS-14667] JDK installation failed on some slaves with InvalidClassException: hudson.tools.JDKInstaller$Platform$1; local class incompatible: …

return a string literal vs a new string object
switching to implicit else