Given:
I have a shared definition and instance data for specific tenants.

When:
I create a report that groups by flow node and deselect the tenant `not defined`

Then:
There is no result data available except for the number of instances

Expected:
Result data should be available.

Hint:
This bug is originating from `ProcessDefinitionReader` where the selected tenants of the report are passed in to retrieve the relevant definition. However as in this case no tenant specific definitions exists no definition is returned and thus all flow node buckets get excluded leading to an empty result.