Update `OutputCaptureRule` so that it now implements
`CapturedOutput` and can be used directly with AssertJ.

Closes gh-17512

Closes gh-17506

* pr/17496:
  Test the Gradle Plugin against Gradle 5.5.1

Closes gh-17496

See gh-17496

* pr/17505:
  Polish

Closes gh-17505

See gh-17505

Align with the recent upstream Spring Framework changes triggered by
their issue #23170.

Closes gh-17492

Setting the log file name to a random value in smoke tests
doesn't work because the logger context has already been initialized.

Closes gh-17486

Using a random value for the logfile name caused
the logfile endpoint to return a 404 as the name
was resolved from the environment on every request.
This commit registers a bean for LogFile which is then
used by the logfile endpoint.

Fixes gh-17434

Closes gh-17025

Fixes gh-17484

* gh-17390:
  Allow build.time to be disabled so BuildInfoMojo's output is repeatable

Closes gh-17390

See gh-17390

Closes gh-17482

* gh-17480:
  Polish AbstractDependsOnBeanFactoryPostProcessor

Closes gh-17480

See gh-17480

Closes gh-17481

* gh-16627:
  Polish "Set up MongoClient beans' dependencies by type rather than name"
  Set up MongoClient beans' dependencies by type rather than name

Closes gh-16627

See gh-16627

See gh-16627

See gh-17128

Closes gh-17479

* gh-17020:
  Polish "Allow depended on beans to be identified by type"
  Allow depended on beans to be identified by type

Closes gh-17020

See gh-17020

Prior to this commit, `AbstractDependsOnBeanFactoryPostProcessor`
could only identify depended on beans by name.

See gh-17020

Closes gh-17478

Closes gh-17476

The `reactor-tools` dependency now brings a new Reactor Debug Agent
which instruments loaded classes for better Reactor stacktraces.
This commit removes the `spring.reactor.stacktrace-mode.enabled`
configuration property since the related Reactor Hook is about to be
removed.
As a replacement, we're introducing `spring.reactor.debug-agent.enabled`
which tells whether the Reactor Debug Agent should be loaded, given that
the `reactor-tools` dependency is available. This option is enabled by
default, since adding the dependency on classpath is a strong signal
already.

Fixes gh-17128

Prior to this commit, having the `spring-boot-starter-rsocket` and the
`jackson-dataformat-xml` dependencies on classpath would result in a
`ClassCastException` when the RSocket auto-configuration tries to
configure Jackson CBOR codecs for RSocket strategies.

This commit disables the Jackson XML support for the CBOR codec in
RSocket.

Fixes gh-17425

This commit uses native Reactor operators `Mono.fromCallable` and
`subscribeOn` for better performance and support.

Fixes gh-17452

* gh-17444:
  Use Assertions.contentOf() where possible

Closes gh-17444

See gh-17444

* gh-17473:
  Add Javadoc `@since` tags for new additional Tomcat connectors methods

Closes gh-17473

See gh-17473