OSS license plugin doesn't include library module licenses

Question

After migrating to Android plugin for Gradle 3.0 the OSS license plugin (https://developers.google.com/android/guides/opensource) no longer includes the licenses from the project's library modules dependencies. Only the "app" module.

I'm using com.google.gms:oss-licenses:0.9.1 and com.google.android.gms:play-services-oss-licenses:11.8.0

If I 'apply' the plugin to all my modules, the third_party_license data is generated in the raw folder for each module. But in the end only the data from the app module end up in the APK.

Is there any workaround for this problem?

Answer 1

Yes that is correct.

Based on my search on how the plugin works, the plugin would generate the data into the res/raw folder of the artifact (aar or apk, but not jar files) based on POM files it can get from the libraries. Then the rest of merging is done by Gradle Android Plugin, and not by the OSS License Plugin, which merges the res folders from all of the sources (dependency libs, modules, main app etc.). However here's is the issue, upon merging, the Android Gradle Plugin would choose one if there are duplicates of the same resource (link to explanation), and the one that is chosen is based on a priority, meaning since both the app module and the lib module are generating the R.raw.third_party_license resource which are duplicates, the one from the app module has a higher priority of being included than the one from the module hence the license information from the module are not included.

There are several ways of fixing this:

1. Include the same dependencies from your library module in your app module. This is probably the worst idea to do but it does not affect your app since Gradle would automatically resolve the dependencies without any issues especially if they will be of the same version, if they were of different versions then Gradle would choose the latest.
2. Rather than using a module dependency, publish the module to a maven repo (locally or remotely, here's a link to show how it could be done locally), and add it's dependency as such: implementation 'com.mygroup:library:1.0'. Don't forget to remove it from the project build.settings file. This would generate the POM file of the library module and hence get the plugin to read it and include it's library licenses. This means that the library should be compiled and published before compiling the app module, but also it could lead to some weird compiling issues and confusions when errors happen.

Unfortunately there is one more way that I thought would work however it didn't. It is by changing the dependencies in your library module to api instead of implementation. This would expose the library dependencies into the app module dependencies but would increase the build time of the project. But finally it didn't generate the raw resources properly because it seems that the OSS License Plugin only reads the dependencies from a POM file of library and in this case the POM file is not being generated even if the library module dependencies were exposed. Probably should post this as an enhancement or bug request to the developers of the plugin.