Fixing `In plugin 'com.google.gms.google-services' type 'com.google.gms.googleservices.GoogleServicesTask' field 'intermediateDir' without corresponding getter has been annotated with @OutputDirectory.`

Today I tried to recompile a very old Flutter project. Besides migrating to Android 1.12, I had to upgrade the Kotlin library and Gradle like in https://www.wafrat.com/fixing-module-was-compiled-with-an-incompatible-version-of-kotlin/. But then I got a new error:

Some problems were found with the configuration of task ':app:processDebugGoogleServices' (type 'GoogleServicesTask').
  - In plugin 'com.google.gms.google-services' type 'com.google.gms.googleservices.GoogleServicesTask' field 'intermediateDir' without corresponding getter has been annotated with @OutputDirectory.

    Reason: Annotations on fields are only used if there's a corresponding getter for the field.

    Possible solutions:
      1. Add a getter for field 'intermediateDir'.
      2. Remove the annotations on 'intermediateDir'.

    Please refer to https://docs.gradle.org/7.4/userguide/validation_problems.html#ignored_annotations_on_field for more details about this problem.
  - In plugin 'com.google.gms.google-services' type 'com.google.gms.googleservices.GoogleServicesTask' field 'packageNameXOR1' without corresponding getter has been annotated with @Input.

    Reason: Annotations on fields are only used if there's a corresponding getter for the field.

    Possible solutions:
      1. Add a getter for field 'packageNameXOR1'.
      2. Remove the annotations on 'packageNameXOR1'.

    Please refer to https://docs.gradle.org/7.4/userguide/validation_problems.html#ignored_annotations_on_field for more details about this problem.
  - In plugin 'com.google.gms.google-services' type 'com.google.gms.googleservices.GoogleServicesTask' field 'packageNameXOR2' without corresponding getter has been annotated with @Input.

    Reason: Annotations on fields are only used if there's a corresponding getter for the field.

    Possible solutions:
      1. Add a getter for field 'packageNameXOR2'.
      2. Remove the annotations on 'packageNameXOR2'.

    Please refer to https://docs.gradle.org/7.4/userguide/validation_problems.html#ignored_annotations_on_field for more details about this problem.
  - In plugin 'com.google.gms.google-services' type 'com.google.gms.googleservices.GoogleServicesTask' field 'quickstartFile' without corresponding getter has been annotated with @InputFile, @Optional.

    Reason: Annotations on fields are only used if there's a corresponding getter for the field.

    Possible solutions:
      1. Add a getter for field 'quickstartFile'.
      2. Remove the annotations on 'quickstartFile'.

    Please refer to https://docs.gradle.org/7.4/userguide/validation_problems.html#ignored_annotations_on_field for more details about this problem.
  - In plugin 'com.google.gms.google-services' type 'com.google.gms.googleservices.GoogleServicesTask' field 'searchedLocation' without corresponding getter has been annotated with @Input.

    Reason: Annotations on fields are only used if there's a corresponding getter for the field.

    Possible solutions:
      1. Add a getter for field 'searchedLocation'.
      2. Remove the annotations on 'searchedLocation'.

    Please refer to https://docs.gradle.org/7.4/userguide/validation_problems.html#ignored_annotations_on_field for more details about this problem.

* Try:
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* Get more help at https://help.gradle.org

BUILD FAILED in 1m 33s

This StackOverflow ticket says we should update GMS but includes no explanation nor how they came up with that version number. I google search led me to https://developers.google.com/android/guides/google-services-plugin, which mentions version 4.3.13. I'd have liked to see a table of Gradle versions and corresponding GMS library versions, but I'll just try that for now.

And... it worked!