See gh-21079

* pr/21054:
  Fix Actuator API PDF name

Closes gh-21054

See gh-21054

* pr/21009:
  Update copyright year of changed file
  Polish

Closes gh-21009

See gh-21009

See gh-21009

* pr/21007:
  Update copyright year of changed files
  Remove this keyword on member method invocations

Closes gh-21007

See gh-21007

See gh-21007

* pr/20992:
  Polish ApplicationHome

Closes gh-20992

See gh-20992

Closes gh-21112

Closes gh-21111

Starting the CouchbaseContainer fails intermittently when creation
of the primary index for the bucket fails with a read timeout. The
test doesn't require a primary index for the bucket so this commit
disables it creation in the hope that it will help to stabilise the
test.

Previously, DefaultResourceLoader instances were created using the
default constructor. This causes the resource loader to capture the
TCCL that was in place at that time. This can lead to a class loader
leak if the resource loader is referenced directly or indirectly from
a static field of a class loaded by a different class loader.

This commit updates the creation of DefaultResourceLoader instances
in main code so that the resource load will use the class loader of
the creating class. In almost all cases this will be the same class
loader as was the thread context class loader that was being captured
so the change in behavior is minimal. Crucially, it will still address
the situation where the TCCL was different.

Note the DevTools' ApplicationContextResourceLoader has been updated
to explicitly use the TCCL. This ensures that it uses the restart
class loader which is required for DevTools to function correctly.

Fixes gh-20900

Closes gh-20823

Close gh-20507 in 2.3.0.RC1

Closes gh-21106

Improve "@ConfigurationProperties vs. @Value" documentation with the
recommendation that kebab-case is used with the `@Value` annotation.

Closes gh-20507

* pr/21104:
  Fix PropertiesMigrationListenerTests

Closes gh-21104

See gh-21104

Closes gh-21105

Refactor `PortInUseException` logic to a single place and refine when
the exception is thrown.

Prior to this commit, we assumed that a `BindException` was only thrown
when the port was in use. In fact, it's possible that the exception
could be thrown because the requested address "could not be assigned".

We now only throw a `PortInUserException` if the `BindException` message
includes the phrase "in use".

Fixes gh-21101

This commit removes changes the timestamp used when writing the
classpath and layers index files in the Gradle plugin to be the
current timestamp unless `preserveFileTimestamps=true`. It also
polishes some duplication in the handling of entry attributes
when creating the fat archive and adds a test to verify that
the Gradle plugin uses the same fixed timestamp constant as
Gradle uses internally.

See gh-21005

Closes gh-21102

Fixes gh-20866

Closes gh-19706

Closes gh-21100

Closes gh-20846

Closes gh-21098

Closes gh-21097

Closes gh-21095

This commit harmonizes our integration of Micrometer's Service Level
objectives.

Closes gh-21076