Description of problem:

As business-central-server.war/WEB-INF/classes/jbpm.console.properties can configure 'Local' for task service:

====
jbpm.console.task.service.strategy=Local
====

I expected that I can use LocalTaskService/SyncWSHumanTaskHandler in business-central so that task operation and process execution can be done in the same transaction.

Actually, it allows me to use LocalTaskService/SyncWSHumanTaskHandler. But those works are still done in different transactions (threads) because StatefulKnowledgeSessionUtil.registerWorkItemHandler() doesn't call SyncWSHumanTaskHandler.setLocal(true).

=====
    private static void registerWorkItemHandler( StatefulKnowledgeSession ksession, Properties consoleProperties ) {
        if ("Local".equalsIgnoreCase(consoleProperties.getProperty("jbpm.console.task.service.strategy", TaskClientFactory.DEFAULT_TASK_SERVICE_STRATEGY))) {
            TaskService taskService = HumanTaskService.getService();
            SyncWSHumanTaskHandler handler = new SyncWSHumanTaskHandler(new LocalTaskService(taskService), ksession);
            ksession.getWorkItemManager().registerWorkItemHandler("Human Task", handler);
        }
=====

Also we have to take into account JBPM-3862. Community jBPM 5.4.0 has LocalHTWorkItemHandler which works in 'local' by default but still task operation and process execution are done in different transactions.

Steps to Reproduce:
1. Configure 'Local'

- Configure jbpm.console.task.service.strategy=Local in business-central-server.war/WEB-INF/classes/jbpm.console.properties

- Add "org.jbpm.task" persistence unit in business-central-server.war/WEB-INF/classes/META-INF/persistence.xml

2. Start BRMS standalone

3. Import repository_export_rollbacktest.xml via Guvnor

4. Login to business-central as john

5. Start a process 'rollbacktest'

6. Complete a Task for john

Actual results:

Process execution will be rolled back. But the Task is committed as "Completed". I observed that with MySQL

Expected results:

Both of task operation and process execution are rolled back. Hence the Taks is rolled back to "Reserved" state.