Make use of lambdas and method references though out the codebase. Remove no longer required generic type parameters.
Additionally remove unused imports and replace single element list initialization with dedicated singletonList.
Use Assertion overloads taking Supplier for dynamic assertion error messages.
We now integrate a best-effort PlatformTransactionManager that will propagate commits and rollbacks to all PlatformTransactionManager instances registered. This assumes that the exceptional cases which will cause a rollback to happen either before the commits or during the first commit.
