add proguard rules to make Jsondadapter annotation work (#2299)

app/proguard-rules.pro

@@ -52,6 +52,14 @@
 }
 
 # https://github.com/google/gson/blob/master/examples/android-proguard-example/proguard.cfg
+
+# Prevent proguard from stripping interface information from TypeAdapter, TypeAdapterFactory,
+# JsonSerializer, JsonDeserializer instances (so they can be used in @JsonAdapter)
+-keep class * extends 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
+
 # Retain generic signatures of TypeToken and its subclasses with R8 version 3.0 and higher.
 -keep,allowobfuscation,allowshrinking class com.google.gson.reflect.TypeToken
 -keep,allowobfuscation,allowshrinking class * extends com.google.gson.reflect.TypeToken