https://stackoverflow.com/questions/44741690/modelcache-computeifabsent-must-not-be-null#
After upgrading to Android Studio 3 Canary 4 I've got this error:
Gradle sync failed: Argument for @NotNull parameter 'key' of com/android/tools/idea/gradle/project/model/ide/android/ModelCache.computeIfAbsent must not be null