This commit restore the use of the `postProcessRequestHeaders` method
when overridden in a custom HttpExchangeTracer implementation.

Closes gh-13924

See gh-13988

* pr/13991:
  Return null immediately when sla is null in convertSla()

Closes gh-13991

Prior to the changes that fixed #12451,
`FilteredPropertySources` and `CompositePropertySources` were required
by the `PropertySourcesDeducer` to ensure that configuration properties binding
could see changes to the environment even when there was a
PropertySourcesPlaceholderConfigurer in the context. #12451 changed the way
property sources are adapted by `SpringConfigurationPropertySources`, removing the
need for `FilteredPropertySources` and `CompositePropertySources`.

Fixes gh-13738

Fixes gh-13965

* pr/13985:
  Upgrade maven wrapper to Maven 3.5.4

Closes gh-13985

* pr/13982:
  Add dependency management for micrometer-registry-cloudwatch

Closes gh-13982

* pr/13963:
  Polish

See gh-13963

This commit makes sure that ServletEndpointRegistrar does not add a
duplicate `/` if the basePath is suffixed with it already

Close gh-13964

* pr/13961:
  Optimize some StringBuilder.append() calls

Closes gh-13961

This commit deprecated the properties of `PooledConnectionFactory` that
are no longer supported by an alternative that is a JMS 2 compliant.

This commit also adds a note to warn users that this pool implementation
is not JMS 2 compliant.

Closes gh-13956

* pr/13933:
  Add classpath prefix to the flyway location

Closes gh-13933

* pr/13952:
  Remove ex.printStackTrace() in tests

Closes gh-13952

Closes gh-13470

Closes gh-13888

Closes gh-13886

Fix checkstyle issues with samples following the
spring-javaformat upgrade.

See gh-13932

Fix checkstyle issues with method ordering following the
spring-javaformat upgrade.

See gh-13932

Fix checkstyle issues in javadoc following the spring-javaformat
upgrade.

See gh-13932

Fix checkstyle issues with ternary expressions following the
spring-javaformat upgrade.

See gh-13932

Closes gh-13932