Protect resources for notifications from stripping

android/app/proguard-rules.pro

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+# This file was taken from
+# https://github.com/MaikuB/flutter_local_notifications/blob/master/flutter_local_notifications/example/android/app/proguard-rules.pro
+
+## Flutter wrapper
+-keep class io.flutter.app.** { *; }
+-keep class io.flutter.plugin.**  { *; }
+-keep class io.flutter.util.**  { *; }
+-keep class io.flutter.view.**  { *; }
+-keep class io.flutter.**  { *; }
+-keep class io.flutter.plugins.**  { *; }
+-dontwarn io.flutter.embedding.**
+
+## Gson rules
+# Gson uses generic type information stored in a class file when working with fields. Proguard
+# removes such information by default, so configure it to keep all of it.
+-keepattributes Signature
+
+# For using GSON @Expose annotation
+-keepattributes *Annotation*
+
+# Gson specific classes
+-dontwarn sun.misc.**
+#-keep class com.google.gson.stream.** { *; }
+
+# Prevent proguard from stripping interface information from TypeAdapter, TypeAdapterFactory,
+# JsonSerializer, JsonDeserializer instances (so they can be used in @JsonAdapter)
+-keep class * implements com.google.gson.TypeAdapter
+-keep class * implements com.google.gson.TypeAdapterFactory
+-keep class * implements com.google.gson.JsonSerializer
+-keep class * implements com.google.gson.JsonDeserializer
+
+# Prevent R8 from leaving Data object members always null
+-keepclassmembers,allowobfuscation class * {
+  @com.google.gson.annotations.SerializedName <fields>;
+}
+
+## flutter_local_notification plugin rules
+-keep class com.dexterous.** { *; }

android/app/src/main/res/raw/keep.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<resources xmlns:tools="http://schemas.android.com/tools"
+    tools:keep="@drawable/*" />