I have generated some building blocks in CityEngine and exported them as "Multipatch feature class" in GeoDataBase, then I imported them into ArcGIS Pro and tried to convert them into 3D GeoJSON format, but it turns out that the "Feature to JSON" tool available in Toolbox does not accept Multipatch feature class, only polygons, polylines, and points. So I first tried to convert the 3D Multipatch feature into Multipolygon, I have tried "Multipatch footprint", which turned out to be losing all the Z values of the building floors. "Feature Vertices To Points" and "Multipatch to Raster" obviously does not suit my purpose.

So how can I convert Multipatch to Multipolygon without losing Z-value, or convert Multipatch into GeoJSON format in general? Thank you in advance if anyone can enlight me on this issue.