* Remove usage of removed `org.springframework.util.SocketUtils`
in favor of OS-selected port
* Migrate mail tests to Greenmail instead of already obsolete (and soon to be removed)
`org.springframework.integration.test.mail.TestMailServer`
* Upgrade to the latest dependencies
* Migrate samples to `jakarta` namespace
* Rework `cafe-scripted` to RSocket instead of already removed RMI
* Migrate JMS samples to Apache Artemis for Jakarta EE 9
* Disables mails tests since there is a requirement to migrate to Greenmail for Jakarta EE 9 support
* Rework `generatePom` task to a new `maven-publish` plugin style
* Use `MatcherAssert.assertThat()`
instead of deprecated `Assert.assertThat()`
* Use `IntegrationFlows.fromSupplier(Supplier)`
instead of removed `IntegrationFlows.from(Supplier)`
* Use `org.springframework.integration:spring-integration-test`
throughout the project for more testing utilities
* update the project with requested changes
* cleaned up commented code
* `travisci` distribution update
* remove transitive dependency
* generate pom
* Fix code format for tab indents
* Add `Jackson2JsonMessageConverter` to avoid Java serialization over the network
