I suggest to implement the following feature:
Expandable Areas are a good feature to hide Detaildata. But the DrillDown-Arrow is allways visible - also when there are NO details.
Please enhance the visible condition with optional formulas (not only yes/no).
A typical use case might be:
To make a report with expandable area smarter for the user, that the user only can click for deail data, if there are detail data.