Closes gh-14190

Closes gh-13865

* gh-14156:
  Polish "OAuth2 client secret should not be required"
  OAuth2 client secret property should not be required

Closes gh-14156

Closes gh-14169

Closes gh-13810

Closes gh-13896

Closes gh-14145

See gh-14184

* pr/14184:
  Polish

Closes gh-14184

Closes gh-8926

Closes gh-14165

Hibernate 5.3 has deprecated the ehcache2 region factory so this commit
upgrades the integration test to use JCache instead.

This reverts commit da4624a8.

This commit fixes the ordering between `CacheAutoConfiguration` and
`HibernateJpaAutoConfiguration` so that the auto-configured
`CacheManager` is configured before Hibernate starts.

Closes gh-14181

This commit introduces a subclass of `DispatcherHandler` that only
considers the current context when looking for WebFlux infrastructure
beans.

This avoids issues where a child context (e.g. with Actuator) picks up
infrastructure beans from the parent context and exposes all endpoints
instead of getting only the ones from the current context.

Closes gh-14012

Closes gh-1789

* pr/14172:
  Polish

Closes gh-14172

This commits restores the behaviour of Spring Boot 1.x with regards to
the "trace" request param used to add the stacktrace to the model.

This was inadvertently changed so that the stacktrace would be added
if the parameter wasn't set.

Closes gh-14171

This commit adds a new auto-configuration choice for
`ClientHttpConnector`, this time using the Jetty RS HTTP client library
if available.

This is the best choice in case the application runs on a Jetty reactive
server, as both client and server will share resources.

Closes gh-14005

This commit adds the Jetty RS HTTP client to the Spring Boot
dependency management. As of SPR-15092 and SPR-17124, this HTTP
client library is supported by Spring Framework.

This commit is first step towards supporting that library as
a driver for the WebClient / ClientHttpConnector auto-configuration.

See gh-14005

This commit makes sure that the auto-configuration for Spring
Integration runs after the datasource has been auto-configured if
necessary as there is an optional part that can initialize the jdbc
schema.

Closes gh-14175

This commit adds support for the new `ReactorResourceFactory` and
ensures that such a bean is created and destroyed with the application
context. This will create a `ClientHttpConnector` bean, to be configured
on the `WebClient.Builder` instance - or let developers create their own
`ClientHttpConnector` bean to override that opinion.

By default, the `ReactorResourceFactory` is configured to participate
with the global resources, for better efficiency.

Closes gh-14058

* pr/14021:
  Polish "Add Kafka Streams auto-configuration"
  Add Kafka Streams auto-configuration

Closes gh-14021

See gh-14021

* pr/13837:
  Polish "Add PropertyMapper.from(value)"
  Add PropertyMapper.from(value)

Closes gh-13837