How to add multiselection DropDown as Uproperty in Details Panel?

Hi ,

I would like to add a multi selection drop down , where user can select more than one condition of an actor class in the Details panel. Kindly let me know how to achieve that. The enum variable lets me select only single option.

Example -
Suppose I am creating a wall using my C++ Actor class , from the details panel, enum lets me decide whether I want to create a wall in the northside, eastside , westside or southside. But if I want to create walls in all sides except , say northside, I cant do that here.