SupportMapFragment does not support AndroidX Fragment
This issue has already been reported to Google in the public issue tracker:
https://issuetracker.google.com/issues/110573930
I would suggest starring the feature request in the public issue tracker to add your vote and subscribe to further notifications from Google. Hopefully, Google will implement it in next versions of Android Maps SDK.
Update
Google has provided the following answer in the public issue tracker
Hi all,
As noted the Google Maps API is currently based off the support libraries and not AndroidX. Future versions of Google Maps API will certainly support AndroidX, but in the meantime, the following workaround will resolve the issue for you:
Use Android Studio 3.2 (currently preview) or higher
Ensure your build.gradle contains 'compileSdkVersion 28' (default for new AS 3.2 projects)
Include the following in your gradle.properties file (default for new AS 3.2 projects)
android.useAndroidX=true
android.enableJetifier=true
Finally, for existing code referencing the support libraries, you can use the "Refactor -> Refactor to AndroidX" tool in Android Studio 3.2+ to automatically convert your code to use the new AndroidX packages.
I had your same problem, fixed by updating all imports to the last version available in the build.gradle file and adding
android.enableJetifier=true
android.useAndroidX=true
To the gradle.properties
this is the version of the maps package I imported
implementation 'com.google.android.gms:play-services-maps:15.0.1'
You just have to fix some imports and then you're done
I hope
EDIT: even after editing what i just said, you will still have the error shown in the java but it compiles and runs without errors
EDIT2: yesterday they suggested a workaround on the issuetracker https://issuetracker.google.com/issues/110573930#comment13