Having a deployment unit in Business Central with PER_PROCESS_INSTANCE session strategy, processes cannot be started via REST, e.g.:
POST http://localhost:8080/business-central/rest/runtime/org.jboss.qa.bpms:clustering:1.0.0.Final/process/clustering.src.main.resources.DoubleHT/start

which ends up with IllegalStateException thrown with message 'No process instance id supplied for operation!'
See the attached stacktrace for more details.

Version-Release number of selected component (if applicable):
6.0.1.CR1

Steps to Reproduce:
1. start a business central
2. create a deployment unit with PER_PROCESS_INSTANCE session strategy
3. try to start any process via REST API