Improve validation of @ConfigProperty/defaultValue for lists and arrays

[angelozerr]

Given this ConfigProperty:

@ConfigProperty(name = "listprop2", defaultValue="12,A,14")
List<Integer> greeting2;

The validation of default value highlights the full String of default value

It should be nice to highlight just A

[fbricon]

I think this is probably overkill and doesn't warrant spending resources on this

[angelozerr]

Fixed with #512