Spring-starter-test now comes with the mighty and useful assertj library. But they still use 2.5.0, which is limited to Java 7 and does not support asserting Optionals for example.
Since this extension requires Java8 from 2.0.0 on, we should switch to the latest (currently 3.5.2) version of assertj.

Copied from https://github.com/camunda/camunda-bpm-spring-boot-starter/issues/164