Closes gh-18205

Closes gh-18226

Closes gh-18225

Previously, the upgrade to Flyway 6 broke compatibility with Flyway
5.2 due to the use of method references that refer to two methods
that do not exist in Flyway 5.2.

This commit replaces the method references with lambdas that are only
called if the user sets the related property. Unless a new-in-Flyway-6
property is set, the auto-configuration will work as before. When such
a property is set the auto-configuration will fail with a
NoSuchMethodError. This approach was chosen to make the
incompatibility clear.

We have also introduced support for passing any JavaMigration beans
in the context into Flyway. This too relies on API that is new in
Flyway 6. It is possible (although unlikely) that users had
JavaMigration beans in Spring Boot 2.1 that were being ignored. This
commit restores this behaviour when using Flyway 5.2.

Closes gh-18193

Closes gh-18222

* pr/18216:
  Fix minor typo

Closes gh-18216

The phrase `We have you covered.` is a sentence and so it should start
with a capital `W`.

See gh-18216

Closes gh-18219

Update `Bindable` builder methods so that existing annotations are
retained.

Closes gh-18218

* pr/18206:
  Polish "Use Duration for ServerProperties.Jetty.idleTimeout"
  Use Duration for ServerProperties.Jetty.idleTimeout

Closes gh-18206

See gh-18206

See gh-18206

* pr/18192:
  Polish

Closes gh-18192

See gh-18192

Closes gh-18209

This commit applies `ServerRSocketFactoryCustomizer` beans to RSocket
setups when the RSocket server is being plugged into an existing Reactor
Netty web server.

Fixes gh-18208

* pr/18196:
  Update Quartz smoke test to use JDBC job store

Closes gh-18196

See gh-18196

Update configuration properties support to allow the `@Component`
annotation to be used on `@ConfigurationProperties` beans as long
as they are mutable.

This restores the behavior of Spring Boot 2.1 for mutable beans whilst
still allowing us to enforce the stricter rules for immutable value
object configuration properties.

Closes gh-18138

* pr/18187:
  Fix typo in javadoc

Closes gh-18187

See gh-18187

* pr/18170:
  Polish "Remove management.health.status.order from docs"
  Fix link formatting in custom HealthIndicator section
  Remove management.health.status.order from docs

Closes gh-18170

See gh-18170

See gh-18170

See gh-18170

This commit moves `@ConfigurationProperties` to the `@Bean` factory
method as this is unusual to put it at class level if it's exposed
that way.

As HealthIndicatorProperties has a constructor, this makes sure that
the annotation processor enables JavaBean binding mode.

This commit makes sure that a ConfigurationProperties type contributed
by a `@Bean` factory method uses properties binding regardless of the
presence of a matching constructor.

`@Bean` method makes sure the user is in control and will be responsible
of creating the instance. As a result, binding of properties will not
happen there and therefore can only happen with regular JavaBean
accessors.

Closes gh-18184

Closes gh-18186

Closes gh-14022

Closes gh-18185

* pr/18175:
  Simplify code

Closes gh-18175

See gh-18175

Closes gh-18182

Closes gh-18181

Closes gh-18180

* pr/18172:
  Fix broken links for master snapshot builds

Closes gh-18172