Closes gh-21159

Closes gh-21158

Closes gh-21157

Closes gh-21156

Closes gh-21155

Closes gh-21154

Closes gh-21153

Closes gh-21152

Closes gh-21151

Closes gh-21150

Closes gh-21149

Closes gh-21148

Closes gh-21147

Closes gh-21146

Closes gh-21145

Closes gh-21144

Closes gh-21143

Closes gh-21142

Closes gh-21141

Closes gh-21140

Closes gh-21139

Closes gh-21138

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

Closes gh-20507

Closes gh-21095

Closes gh-21084

Add how-to documentation describing how health information can be
exported to a Micrometer Gauge.

Closes gh-18329

Closes gh-19782

Update `JarURLConnection` to ensure that when connections are opened
a new copy of the JarFile is provided.

Prior to this commit, a single `JarFile` instance was shared which meant
that it could be accidental closed if accessed via
`JarURLConnection.getJarFile()`. If the underlying jar file is closed
then it's possible for a `NoClassDefFoundError` to be thrown if running
on JDK 11 with an active `SecurityManager`.

Closes gh-17796

Update `WebMvcAutoConfiguration` to automatically apply cors
configuration to the `WelcomePageHandlerMapping`.

Fixes gh-21048

Update `NettyWebServer` so that the `PortInUseException` is not thrown
for permission denied errors.

Fixes gh-19807

Update classes that throw `PortInUseException` so that they also
include the cause. Prior to this commit the cause was not included
which could make diagnosing the real cause difficult.

See gh-19807

Update the reference documentation with more details about how relaxed
binding works against environment variables.

Closes gh-18215

Closes gh-19972

Update `ExposeExcludePropertyEndpointFilter` so that patterns will
also match endpoint IDs that contain a dash.

Closes gh-20997

Refine `DataSourceAutoConfiguration` conditions so that an empty
`spring.datasource.url` property can be used to enable the embedded
source.

Fixed gh-20996

Closes gh-20978

Closes gh-20976

Closes gh-20623