HibernateJpaVendorAdapter and LocalSessionFactoryBuilder enforce Hibernate 5.2's connection handling mode DELAYED_ACQUISITION_AND_HOLD

Issue: SPR-14393

Issue: SPR-14393

Issue: SPR-14327

Issue: SPR-14246

Closes gh-1039

Issue: SPR-13886

Includes a fix for Query unwrapping before passing it to addNamedQuery.

Issue: SPR-13960
Issue: SPR-13957

Issue: SPR-13838

Issue: SPR-13732

Background bootstrapping via "bootstrapExecutor" for  LocalContainerEntityManagerFactoryBean and LocalSessionFactoryBean/Builder

Issue: SPR-13732

Issue: SPR-13744

- Delete unused imports
- Delete unused code
- Clean up warnings

Issue: SPR-13230

Issue: SPR-13621

This is in preparation for a migration from JUnit 3 to JUnit 4.

Issue: SPR-13514, SPR-13515

This commit migrates all remaining tests from JUnit 3 to JUnit 4, with
the exception of Spring's legacy JUnit 3.8 based testing framework that
is still in use in the spring-orm module.

Issue: SPR-13514

HibernateJpaDialect logs warning in case of Connection mismatch (e.g. configured release mode other than ON_CLOSE)

Related to that, HibernateTransactionManager specifically checks for active physical connections on reset as of Hibernate 5.

Issue: SPR-13269
Issue: SPR-13002

Issue: SPR-13243

Issue: SPR-13242

Issue: SPR-13040

Issue: SPR-12926

Issue: SPR-11694

Issue: SPR-11694

(cherry picked from commit 673dac56)

Covers ReflectionUtils.doWithMethods as well as affected annotation post-processors.
Includes an extension of MethodMetadata for the detection of @Bean default methods.

Issue: SPR-12822
Issue: SPR-10919

- Using Javadoc syntax for code formatting instead of JIRA's.

Issue: SPR-12821

Issue: SPR-8959
(cherry picked from commit 0280a2a9)

Issue: SPR-12766

This commit suppresses warnings in test classes that were polluting the
Gradle build output.