String option is empty string by default and not null

[georgmittendorfer]

In spring shell 3.x an option @Option(longName = "test", description = "some description") String test was null when not specified. In spring shell 4.x it is an empty string "". That breaks old behavior and seems to be counter intuitive for me. I assume it is a bug. If that is wanted behavior feel free to close this issue.

[piotrooo]

I think this is a more complex issue than just handling strings and is related to general type and value handling (ref: #1262).

We should rethink how we handle all possible option types and their values.

[fmbenhassine]

Thank you for reporting this, @georgmittendorfer . I seem to have missed that difference between v3 and v4. I will fix that.

@piotrooo Thank you for the follow up! #1262 has been resolved and Spring Shell now uses the default values assigned by Java to primitive types. For non primitive types, I will update the code like in v3 and set null as default value if no default value is present.