Thank you for your replies. I understand your argumentation.
But I think I will keep my JAXB solution. I think I can justify this decision in the choices.txt.
In fact, I find it more simpler and less error-prone to use JAXB. My options class has getters like this:
And persisting such options looks like this:
And that's it. The file is called "suncertify.properties".
I think this solution is also a very simple way.
Maybe soon I will regret this decission
Once again. Thank you for your statements.