Steps to reproduce

1. Model an external task process and assign a version tag
2. Deploy the process model
3. Start an instance of the process
4. Query for external tasks

Expected behavior

I can see the version tag in the result set of the external task query

Observed behavior

The version tag in the result set of the external task query is null.

Root cause

The SQL query selectExternalTaskByQueryCriteriaSql does not select the version tag information

Solution

1. Adjust the selectExternalTaskByQueryCriteriaSql to join over ACT_RE_PROCDEF
2. Add VERSION_TAG_ to the column selection of selectExternalTaskByQueryCriteriaSql and selectExternalTaskByQueryCriteria (columnSelection)

Hint

See the failing test case:
https://github.com/camunda/camunda-bpm-platform/commit/d7572f815180aaab37e6515f8a76b3a4c761e387