As HibernateJpaConfiguration is package private, it is no longer
possible to extend the default Spring Boot configuration to apply
advanced settings. The most notable use case for this is the
customization of Hibernate properties using instance value vs. string
value that can be set using the "spring.jpa.properties" namespace.

This commit adds a HibernatePropertiesCustomizer callback interface that
can be implemented to tune Hibernate properties at will.

Closes gh-11211

Closes gh-11508

See gh-11510

* pr/11510:
  Polish

Closes gh-11510

Fixes gh-11383

See gh-10516

Fixes gh-10516

See gh-11503

See gh-11501

This reverts commit f91f8f7e.

See gh-11475

* pr/11489:
  Polish
  Full editing pass plus linking

I made a complete editing pass plus another pass to see where I could add more links, both within the document and to other parts of Spring. The result was a thorough edit (though I'm sure I missed things, purely due to the size of the thing).

Closes gh-10133

Closes gh-11490

This commit shades the json API in the configuration processor so that
it doesn't bring `android-json` to the classpath anymore.

Closes gh-10307

Change `CacheMeterBinderProvider` to include a cache type
generic which helps to simplify implementations. Also move
and extract a few classes.

See gh-11221

Update the validator background initializer to actually create
the validator.

Closes gh-11412

This commit configures Jetty for HTTP/2 support as soon as the following
conditions are met:

* `server.http2.enabled=true`
* Both `org.eclipse.jetty:jetty-alpn-conscrypt-server` and
`org.eclipse.jetty.http2:http2-server` are on classpath

This will use the Conscrypt library for ALPN and TLS support using
native libraries shipped within the Conscrypt uber Jar. This does not
require a JVM agent or patching the JDK classes.

Closes gh-10902

See gh-11235

Closes gh-11221

Closes gh-11483

Closes gh-11482

Closes gh-11481

Closes gh-11480

Closes gh-11479