Rather than disabling checkstyle altogether, this commit enables it
again, relaxing the javadoc requirement only.

See gh-7142

Closes gh-7142

Closes gh-7147

Closes gh-7044

* pr/6666:
  Polish contribution
  Add Rabbit idleEventInterval property

Closes gh-6666

This commit adds a property to configure how often idle container events
should be published.

See gh-6666

* pr/6645:
  Polish contribution
  Add workingDirectory option for Maven plugin run/start

Closes gh-6645

Add configuration option that specifies the working directory to use to
run/start the application via the Maven plugin.

Closes gh-6243

Closes gh-7138

* pr/7137:
  Add missing parentheses

Closes gh-7137

Closes gh-2642

* pr/6571:
  Polish contribution
  Manage Tomcat queued connections

Closes gh-6571

Adding two tomcat server properties:
- server.tomcat.accept-count
- server.tomcat.max-connections

Closes gh-6433

* pr/6543:
  Polish contribution
  Improve database initializers

Closes gh-6543

This commit improves database initializers for Spring Batch and Spring
Session by introducing `AbstractDatabaseInitializer` which eliminates
duplicated logic in existing initializers. Additionally, database
platform resolution now relies on `DatabaseDriver`.

See gh-6543

Note: the fully-qualified references to @Configuration in some of the
test configuration classes are required to work around a bug in javac.
1.8.0_102 (and earlier). Without them, compilation fails as it cannot
resolve the symbol despite the import statement and the unqualified
references working elsewhere in the same source file.

Closes gh-7056

See gh-7080

* pr/7127:
  Fix typo

Closes gh-7127

Closes gh-7113

Closes gh-6823

* pr/7120:
  Fix String.format() usages