We tend to be quite skeptical of business process model and notation (BPMN) tools in general as they're often associated with low-code environments and their downsides. Although the OSS BPMN framework Camunda provides some of this whizziness, it also offers workflow and decision engines that can be directly integrated as a library in your Java code. This makes it easy to test, version and refactor workflows. Camunda also integrates with Spring and Spring Boot, among other frameworks, making it a solid choice.