Also suffering from this issue:
Blockquote
Could not resolve com.google.android.gms:play-services-ads-base:[17.2.0].
Required by:
project :app > com.google.android.gms:play-services-ads:17.2.0
project :app > com.google.android.gms:play-services-ads:17.2.0 > com.google.android.gms:play-services-ads-lite:17.2.0
project :app > com.google.android.gms:play-services-ads:17.2.0 > com.google.android.gms:play-services-gass:17.2.0
Failed to list versions for com.google.android.gms:play-services-ads-base
> Could not get resource 'https://jcenter.bintray.com/com/google/android/gms/play-services-ads-base/maven-metadata.xml'.
> Could not GET 'https://jcenter.bintray.com/com/google/android/gms/play-services-ads-base/maven-metadata.xml'. Received status code 502 from server: Bad Gateway