API 'variant.getMergeResources()' is obsolete and has been replaced with 'variant.getMergeResourcesProvider()'

Two versions of the Google Services Gradle Plugin (4.3.0 & 4.3.1) are causing this, upgrading the version to 4.3.2 seems to solve the issue;

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In your project-level build.gradle file, under buildscript -> dependencies, check whether you have this line

classpath 'com.google.gms:google-services:4.3.x'

if so, change it to

classpath 'com.google.gms:google-services:4.3.3'

Edit: Click here to check the newest version. (4.3.3) at time of Edit.

Is a known issue, will be fixed on the next release:

https://github.com/google/play-services-plugins/issues/65

https://github.com/google/play-services-plugins/pull/62