Review on ConfigurationPropertiesBeanDefinition

[snicoll]

There is a leftover of a review on ConfigurationPropertiesBeanDefinition that we should address.

[philwebb]

I've removed the FIXME for now so we can release, but I'd like to take another look at this. I have a feeling we might be able to move some of the logic from ConfigurationPropertiesBeanDefinition and ConfigurationPropertiesBindingPostProcessor into ConfigurationPropertiesBinder.

[mbhave]

@philwebb If you haven't started on this already, might be better to wait till we decide what to do in #16712.

[snicoll]

@philwebb this issue is now ready as #16712 has been declined.