See forum discussion http://forums.activiti.org/en/viewtopic.php?f=8&t=1100&p=4484#p4484
Activiti designer seems to NOT generate <usertask /> XML when generating the bpmn2.0 xml. I'm using v0.7 of designer that comes with activiti r5.2.
here's the test that brings up this issue:
1) create a main process as:
2) elaborate subprocess as:
At this point, the bpmn2.0 xml contains the <sequenceflow /> tags correctly. However, the usertasks in subprocess that the sequence flow refers to are missing.
Attached is the xml used for this test. This also happens when deleting and adding usertasks in the subprocess.
This is seen as an error message like: "cvc-id.1: There is no ID/IDREF binding for IDREF 'xxxx'
Activiti 5.2/ Spring source tool suite 2.5.1/ Tomcat 6.0.29