Interoperability between `protobuf-javalite` and `protobuf-java`

[viktor-kostadinovski]

The problem

Clients using protobuf-java instead of protobuf-javalite have to migrate their codebase to protobuf-javalite in order to integrate with PlaidSDK
The PlaidSDK is using protobuf-javalite, which expects GeneratedMessageLite classes, while our project is using protobuf-java, which works with GeneratedMessage classes (such as Struct). This mismatch unfortunately causes the verifier to reject the class during runtime, as it’s expecting GeneratedMessageLite but encountering a class from protobuf-java instead , which is the Struct.
This leads to the following error :

java.lang.NoSuchMethodError: No virtual method build()Lcom/google/protobuf/GeneratedMessageLite; in class Lcom/google/protobuf/Timestamp$Builder; or its super classes (declaration of 'com.google.protobuf.Timestamp$Builder' appears in /data/app/~~kr4cSZrPd_dXG0MQKGpZDQ==/com.kaching.merchant.dev0-yhGyMQvWrSi28Sq9If92wg==/base.apk!classes39.dex)
                                                                                                    	at com.plaid.internal.xk.a(SourceFile:106)
                                                                                                    	at com.plaid.internal.z8.a(SourceFile:3436)
                                                                                                    	at com.plaid.internal.z8$j.invokeSuspend(SourceFile:1)

We have encountered similar cases and there is multiple solutions to support clients that use protobuf-java as well as protobuf-javalite

Possible solutions :

• PlaidSDK keeps using protobuf-javalite but generate the protobuf files for protobuf-java , i.e. generate the classes from the .proto files to be compatible with protobuf-java ( i.e. Use Struct instead of GeneratedMessageLite for example)
• additionally include the dependency : com.google.firebase:protolite-well-known-types , which includes (the Struct for example). That way a client using protobuf-javalite can simply integrate
  and a client using protobuf-java , can simply exclude the dependencies , similar to firebase-performance
  like :

 implementation(FirebasePerformance) {
        exclude(group = "com.google.protobuf", module = "protobuf-javalite")
        exclude(group = "com.google.firebase", module = "protolite-well-known-types")
    }

Since protobuf-java already includes these well-known-types, that’s the most minimally invasive option to accommodate SDK integrators in both cases.

• We have also seen SDK providers that offer 2 versions , one with protobuf-java and one with protobuf-javalite, however that requires maintaining both versions , so its not the most direct approach.

Useful links :

protocolbuffers/protobuf#8104
firebase/firebase-android-sdk#5997 (comment)
https://github.com/firebase/firebase-android-sdk/tree/main/protolite-well-known-types#problem

Environment

Android OS Version	e.g. 13.0.0 (21)
Android Devices/Emulators	e.g. Pixel 6a emulator

Expected Result

Should not be required to change our dependencies for protobuf.