Closes gh-10200

Previously, if a user's configuration class provided a custom
Validator bean, that configuration class would be initialized very
early so that the Validator could be used to create the
auto-configured MethodValidationPostProcessor. This early
initialization could problems as it may prevent any of the
configuration class's dependencies from being post-processed.

This commit updates the injection of the Validator bean to be lazy,
thereby preventing the creation of the auto-configured
MethodValidationPostProcessor from triggering early initialization.

Closes gh-9416

Closes gh-9956

Previously, when DevTools encountered a jar with a Class-Path manifest
attribute that referenced non-existent files, it would log one
message per entry in the attribute that did not exist. While useful
information, this has proven to be too verbose.

This commit aims to strike a better balances by logging a single
message for an entire jar. The message is a single line that
includes the path to the jar with the faulty Class-Path manifest
attribute and the paths of all of the files that do not exist that are
referenced by the attribute.

Closes gh-10111

Closes gh-10197

Closes gh-10196

Closes gh-10195

Closes gh-10194

Closes gh-10193

Closes gh-10192

Closes gh-10191

Closes gh-10190

Closes gh-10189

Closes gh-10188

This commit makes sure to backoff if a Client bean is not available.

Closes gh-10143

* pr/10130:
  Polish "Improve exception message for invalid source"
  Improve exception message for invalid source

Closes gh-10130

See gh-10130

Fixes gh-10105

Closes gh-10175

Closes gh-10114

See gh-10165

Closes gh-10022

* pr/10084:
  Identify and fix incomplete assertions

Several calls to assertThat lacked a following assertion most often due
to wrong use of parenthesis.

See gh-10084

Closes gh-10102

See gh-10088

Fixes gh-10013

* pr/10058:
  Add Stripes Spring Boot starter reference

Closes gh-10058

* pr/10050:
  Document default values for compression properties

Closes gh-10050

Neo4jDataAutoConfiguration is meant to kick in when Spring Data Neo4J is
on the classpath. Yet, we were only checking for the presence of neo4j
itself and the transaction manager provided by spring-tx.

This commit makes sure to back off if Spring Data Neo4J is not present.

Closes gh-10038

This reverts commit 0e645988

Closes gh-10034

This commit makes sure to prevent the Freemarker web auto-configuration
to kick in if `spring-webmvc` is not on the classpath.

Closes gh-10027

Closes gh-10026

* pr/10012:
  Polish "Add link to AMQP 1.0 JMS Binding Spring Boot starter"
  Add link to AMQP 1.0 JMS Binding Spring Boot starter

Closes gh-10012