It looks like a temporary issue, the server with these libraries is down. I have the same problem now with Room:
Could not GET 'https://google.bintray.com/exoplayer/androidx/room/room-common/maven-metadata.xml'. Received status code 502 from server: Bad Gateway
You can try using offline mode if you’re using Android Studio, then it will use the cached version of this library if you have it until it is fixed.
UPD. I switched to an alpha version of a flutter lib which caused this (workmanager) and it works well now. As far as I understand it was depending on an old version of Android Room library which is not available anymore since Bintray is not available. The new version of Room is available as it’s being downloaded thorough another link. So for you the solution could be updating to a newer version of Flutter location package or forking it and changing the version of play-services-location to the most recent one.