Closes gh-3419

Closes gh-3286

* pr/3431:
  Polish AMQP doc
  Add AMQP section to the documetation

Closes gh-3431

Closes gh-3348

* pr/3429:
  Fix deployment title section

Closes gh-3429

* pr/3428:
  Fix typo

Closes gh-3428

* pr/3370:
  Fix Restarter.setEnabled() to use parameter

Closes gh-3370

* pr/3374:
  Extend TemplateViewResolverProperties for Groovy

Use AbstractTemplateViewResolverProperties as the base class for
GroovyTemplateProperties since the Spring GroovyMarkupViewResolver is
an AbstractTemplateViewResolver.

The auto-configuration for Groovy is now more aligned with the existing
Freemarker and Velocity auto-configuration, with a `resourceLoaderPath`
property being used instead of `prefix`.

Fixes gh-3365
Closes gh-3374

* pr/3414:
  Clarify MultipartConfigFactory javadoc

Update MultipartConfigFactory javadoc to make it clear that you are
passing in the size in bytes.

Fixes gh-3414

Update ConfigFileApplicationListener to use the recently introduced
DeferredLog class rather than storing its own log messages.

Previously, all attempts to log a configuration file were logged at DEBUG
level which lead to a lot of noise as Spring Boot looks in many places by
default.

We now only log the files that are effectively found at DEBUG level and
all failed attempts at TRACE level.

Closes gh-3129

Previously, if the repackaged file was different from the main artifact
of the build, the maven plugin wrongly considered that it should attach
the file with a classifier.

The outputDirectory is honored properly now, regardless of the fact a
classifier is defined or not.

Fixes gh-3177

* pr/3409:
  Polish
  Add mail server connection check

Polish 383e94c to validate any `JavaMailSenderImpl` and not only the
one that has been created by auto-configuration.

Closes gh-3409

If a `JavaMailSenderImpl` is available, check that the underlying mail
server is available on startup. Add a `spring.mail.test-connection`
property to control this behaviour.

Closes gh-3408

Closes gh-3322

Make sure to fail the build with a proper compilation error message if
the user-defined meta-data are invalid. For now, this takes care of the
JSON format but other checks may be added in the future.

Closes gh-3329

Clarify how the default JMS listener container factory is created if none
exists with regards to transactions.

Issue: SPR-3407

Closes gh-3412

See gh-1390

See gh-3391

Rework RandomValuePropertySource class javadoc, particularly the
description of the `random.int` range suffix.

Also add support for range based random longs.

Fixes gh-3391