Spring Integration AWS
Spring Integration Extensions
Tests: 32 passed
Duration: 1 minute
Changes: Who: Artem Bilan
Why: GH-157: Fix `optional` dependencies for pom
Fixes https://github.com/spring-projects/spring-integration-aws/issues/157

It turns out that `implementation` provides a `runtime` dependency in
Maven"s POM, which is not what we would expect to behave as an `optional`

* Apply Gradle variants for those dependencies which should be as
`optional` in the generate POM
* Some Gradle build config refactoring
Changes by Artem Bilan