Add Google Java API proguard rules

app/build.gradle.kts

@@ -34,7 +34,7 @@ android {
     defaultConfig {
         testApplicationId = "org.tasks.test"
         applicationId = "org.tasks"
-        versionCode = 609
+        versionCode = 612
         versionName = "6.9"
         targetSdkVersion(Versions.targetSdk)
         minSdkVersion(Versions.minSdk)

app/proguard.pro

@@ -61,3 +61,16 @@
 -dontwarn com.amazon.**
 -keep class com.amazon.** {*;}
 -keepattributes *Annotation*
+
+# https://github.com/google/google-api-java-client-samples/blob/34c3b43cb15f4ee1b636a0e01521cc81a2451dcd/tasks-android-sample/proguard-google-api-client.txt
+-keepattributes Signature,RuntimeVisibleAnnotations,AnnotationDefault
+-keepclassmembers class * {
+  @com.google.api.client.util.Key <fields>;
+}
+-dontwarn com.google.api.client.extensions.android.**
+-dontwarn com.google.api.client.googleapis.extensions.android.**
+-dontwarn com.google.android.gms.**
+-dontnote java.nio.file.Files, java.nio.file.Path
+-dontnote **.ILicensingService
+-dontnote sun.misc.Unsafe
+-dontwarn sun.misc.Unsafe