This commit modularizes spring-boot-test-autoconfigure. It now
contains only the code that's central to test auto-configuration.
Feature-specific functionality has moved out into -test modules,
some existing and some newly created. For example, `@DataJpaTest` can
now be found in spring-boot-data-jpa-test.
Closes gh-47322
This commit removes OptionalParameter in favor of the nullness support
introduced in Spring Framework 7. The parameter of an action can now
be flagged as optional using JSpecify's @Nullable, and simplifies the
setup for those who are using JSpecify as only a single annotation is
required.
Closes gh-45390
Moritz Halbritter
Andy Wilkinson
Stéphane Nicoll
Phillip Webb