Replaced Map synchronization with ConcurrentHashMap to avoid session access deadlocks

Issue: SPR-10436
Fixed BeanPropertyRowMapper to only prefix actual upper-case letters with underscores

Issue: SPR-10547
Avoid NPE in ContextLoader when dealing with an untyped ApplicationContextInitializer

Issue: SPR-10449
Consistent use of Class<?> in Assert
Consistent detection of Order annotation in superclasses and interfaces

Issue: SPR-10514
Add partial WebSocketMessage support
Fix bug in WebSocketClient implementations
Enforce JDK version on CI server

Add a test to ensure that the CI server does not accidentally build
with the wrong JDK version.

Issue: SPR-10569
Release version 4.0.0.M1
Increment version to 4.0.0.BUILD-SNAPSHOT