we provide a simple layer on top of the jBPM5 Human Task component to expose it using the WSDL from the WS-HT specification. You can use this simple layer adding the smart tasks dependency to your project. You can check out the source code here: https://github.com/Salaboy/smart-tasks/tree/master/smart-tasks-model/src/main/resources/wsdl (the where the WSDL from the specs are)
and here: https://github.com/Salaboy/smart-tasks/tree/master/smart-tasks-api for the projects that expose this apis.
The snapshots for this projects are hosted in plugtree repositories in cloudbees repositories. Just in case that you don't want to compile the source code.