Beyond just formally declaring the current behavior, this revision actually enforces non-null behavior in selected signatures now, not tolerating null values anymore when not explicitly documented. It also changes some utility methods with historic null-in/null-out tolerance towards enforced non-null return values, making them a proper citizen in non-null assignments.
Some issues are left as to-do: in particular a thorough revision of spring-test, and a few tests with unclear failures (ignored as "TODO: NULLABLE") to be sorted out in a follow-up commit.
Issue: SPR-15540
Prior to this change, spring-beans contained its own META-INF containing
spring.handlers and spring.schemas files in src/main/resources; it also
had files of the same name within src/test/resources/META-INF, causing
'duplicate resource' warnings and confusion in general.
This commit moves the com.foo test package, it's associated namespace
parsing tests and test versions of META-INF files to the root project
and it's src/test integration testing folder.
Issue: SPR-9431
Juergen Hoeller
Stephane Nicoll
Chris Beams