Formatting a Custom Build Summary Section

I'm creating a custom section in my Build Summary that will display detailed code coverage information, using the CustomSummaryInformation object within a CodeActivity to create the section.

Is there formatting that I can add to the message to create collapsible sections within the message?

My goal would be to have an overview displayed the coverage per solution, which can be expanded to show the coverage for each assembly within that section.

-> Solution 1 - 1% covered

--> Assembly 1 - 2% Covered

--> Assembly 2 - 2% Covered

-> Solution 2 - 100% covered

--> Assembly A - 100% covered

--> Assembly B - 100% covered