Introduce OptionalToObjectConverter #34544
Description
Overview
We have an ObjectToOptionalConverter since Spring Framework 4.1; however, we do not have a standard Converter for the inverse.
As discussed in #20433 (comment), it would beneficial to have an OptionalToObjectConverter.
Although its primary use would likely be in SpEL expressions, we should investigate whether it makes sense to register it by default in DefaultConversionService, especially since doing so would allow the OptionalToObjectConverter to be package-private like ObjectToOptionalConverter.