* patch-1:
  Unescape quotation marks in JavaDoc

Closes gh-6482

Switch `@AutoConfigureJsonTesters` to use regular `@Autowired` injection
for JSON testers. Prior to this commit JSON Tester fields were
initialized directly which caused IDE issues and was also a little
confusing.

Fixes gh-6451

Closes gh-6480

Closes gh-6481

Closes gh-6479

Closes gh-6478

Closes gh-6477

Closes gh-6476

Closes gh-6475

Closes gh-6474

Closes gh-6473

Closes gh-6472

Closes gh-6471

Closes gh-6470

Closes gh-6469

* gh-6459:
  Upgrade to Lombok 1.16.10

Closes gh-6459

Closes gh-6468

Closes gh-6467

Closes gh-6466

* gh-6458:
  Upgrade to Spring Integration 4.2.9.RELEASE

Closes gh-6458

This commit adds a new configuration key:

    spring.http.encoding.mapping.<locale>=<charset>

This allows to specify which default charset should be used for any
given Locale, if none has been provided already in the response itself.
This applies to all supported embedded servlet containers.

Fixes gh-6453

* pr/6462:
  Move "Using jOOQ" section under "Working with SQL databases" section

Closes gh-6462

* SI-4.3.1:
  Upgrade to Spring Integration 4.3.1

Closes gh-6456

* multi-datasource:
  Add JdbcTemplate only on single DataSource
  Add TransactionManager only on single DataSource

Update auto-configuration logic so that a `JdbcTemplate`
is only added when there is a single candidate DataSource bean.

Closes gh-6449

Update auto-configuration logic so that a `DataSourceTransactionManager`
is only added when there is a single candidate DataSource bean.

See gh-6449

Move ApplicationPidFileWriter and EmbeddedServerPortFileWriter to the
core spring-boot project since they're not really tied to the actuator.

Fixes gh-6398

Update @AutoConfigureMockMvc to support extended print options including
`System.err` and `log.debug`. In addition the "default" print option
can now be overridden by adding `spring.test.mockmvc.print=...` to
`src/test/resources/application.properties`.

Fixes gh-6455

Update @PropertyMapping support to allow single enum values to be marked
as an @UnmappedPropertyValue. This change is primarily so that users can
replace "default" values globally for across all tests.

See gh-6455

* checkstyle:
  Remove severity elements from checkstyle.xml

Remove `error` severity elements from `checkstyle.xml` and rely on the
default setting instead.

Closes gh-6442