Google Open Buildings is a valid source

[Marc-marc-marc]

https://github.com/OSMBrasil/validador-josm/blob/master/Rules_Brazilian-Specific.validator.mapcss#L1039
https://www.openstreetmap.org/way/1281860067
source=Google Open Buildings
but Google Open Buildings has the ODbL as one of its licences, which makes it compatible with osm