In particular, avoid accidental usage of ASM for core JDK types - which will fail in case of a new bytecode version in the JDK, even if the application itself has been compiled with an earlier bytecode target.

Issue: SPR-10292

Issue: SPR-10129

This commit eliminates the 'integration-tests' subproject in favor of
managing these sources under the root project's own 'src' directory.

This helps to avoid special-case handling for integration-tests in the
Gradle build, e.g. avoiding publication of jars to Artifactory /
Maven Central.

It is also semantically more correct. This is not a Spring Framework
subproject so much as it is a collection of integration tests that
span functionality across many subprojects. In this way, it makes
sense to place them directly under the root project.

Issue: SPR-8116

See EnableCaching Javadoc for details.

Issue: SPR-8312