Previously \r\n was used on Windows and \n was used on other
platforms. This resulted in different JSON content being written to
the archive. As the config's entry name is the SHA-256 hash of its
content, it also resulted in the entry name being different.

This commit updates the JSON that's written into the archive to use
\n line endings, irrespective of the OS on which the image is being
built.

See gh-19828

See gh-19828

* gh-19863:
  Fix TestFailuresPlugin.TestFailure.compareTo()

Closes gh-19863

This commit also polishes around it a bit.

See gh-19863

We build with Java 8, 11, and 13 without specifying target
compatibility for the bytecode of the app that's placed in the image.
The built image uses Java 11 and when the app is built with Java 13
it fails to start as the Java 11 VM can't read that Java 13 bytecode.

This commit configures the app that's placed in the image to be built
with target compatibility of 1.8. This allows it to be compiled with
all version of Java with which we build and to also be compatible
with the JVM that's in the image.

See gh-19831

Closes gh-19874

Closes gh-19824

https://repo.spring.io/snapshot should only be available when
building a BUILD-SNAPSHOT. https://repo.spring.io/milestone should
only be available when not building a RELEASE (a BUILD-SNAPSHOT, Mn,
or RCn).

Closes gh-19700

Closes gh-19867

Closes gh-19792

Closes gh-19831

See gh-19847
See gh-19792

This commit changes uses of ClassLoader.loadClass to Class.forName for
consistency with what was initiated in #19342 and better compatibility
with GraalVM.

Closes gh-19824

* pr/19764:
  Upgrade to Kafka 2.4.0 and Spring Kafka 2.4.1

Closes gh-19764

See gh-19764

Closes gh-19650

Closes gh-19873

Closes gh-19872

* pr/19855:
  Polish "Encourage use of SpringBootApplication"
  Encourage use of SpringBootApplication

Closes gh-19855

See gh-19855

See gh-19855

Closes gh-19871

Closes gh-19856

Closes gh-19870

Closes gh-19869

Closes gh-19857

Update the `Packager` to automatically add the layertools jarmode jar
when producing a layered jar.

Closes gh-19865

Update `LaunchedURLClassLoader` to ensure that the `JarModeLauncher`
is created in the correct classloader.

Prior to this commit the launcher was created by the application
classloader and did not have access to any of the required
`org.springframework` classes.

See gh-19848

Rename `spring-boot-layertools` to `spring-boot-jarmode-layertools`.

Closes gh-19853

Closes gh-19847

This class was mistakenly marked as deprecated in 2.2.0 instead of deprecated
in 2.3.0. This resulted in the class being deleted as part of the 2.3.0
cleanup.

Putting it back in place now with the correct deprecation noted.

Closes gh-19861

Update all dependencies declarations to use the form `scope(reference)`
rather than `scope reference`.

Prior to this commit we declared dependencies without parentheses unless
we were forced to add them due to an `exclude`.

Replace Gradle single quote strings with the double quote form
whenever possible. The change helps to being consistency to the
dependencies section where mostly single quotes were used, but
occasionally double quotes were required due to `${}` references.

The Spring Cloud Connectors project has been deprecated in favor of the
Java CFEnv project. The Boot auto-configuration and starter that support
Connectors were deprecated in Boot 2.2.

This commit removes the Connectors auto-configuration, starter,
and dependency management.

Closes gh-19798

Closes gh-19792
Co-authored-by: Andy Wilkinson <awilkinson@pivotal.io>

This change ensures that each test in a test suite that shares an
application context gets a unique embedded database, to prevent
inconsistent embedded database state between tests.

Closes gh-16747