Realm release build with proguard fails - Could not find io.realm.RealmHelper - realm

Question

We're getting ready to release our first app with realm and, oops, finally tried a release build. Everything works fine until we enable proguard, then the app crashes on launch with:
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example/com.example.activities.IntroActivity}: io.realm.exceptions.RealmException: Could not find io.realm.RealmHelper$ManifestModuleMediator
...
Caused by: io.realm.exceptions.RealmException: Could not find io.realm.RealmHelper$ManifestModuleMediator
at io.realm.y.a(Unknown Source)
at io.realm.y.a(Unknown Source)
at io.realm.y.<init>(Unknown Source)
at io.realm.y.<init>(Unknown Source)
at io.realm.z.a(Unknown Source)
at com.example.realm.RealmHelper.a(Unknown Source)
at com.example.activities.IntroActivity.onCreate(Unknown Source)
We're using the realm recommended proguard settings, i.e.:
-keep class io.realm.annotations.RealmModule
-keep #io.realm.annotations.RealmModule class *
-keep class io.realm.internal.Keep
-keep #io.realm.internal.Keep class * { *; }
-dontwarn javax.**
-dontwarn io.realm.**
Any suggestions? Unfortunately we don't have any proguard wizards...
FWIW, I tried adding this line to the proguard config:
-keep class io.realm.** { *; }
That changed the trace to:
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example/com.example.activities.IntroActivity}: io.realm.exceptions.RealmException: Could not find io.realm.RealmHelper$ManifestModuleMediator
...
Caused by: io.realm.exceptions.RealmException: Could not find io.realm.RealmHelper$ManifestModuleMediator
at io.realm.RealmConfiguration.getModuleMediator(Unknown Source)
at io.realm.RealmConfiguration.createSchemaMediator(Unknown Source)
at io.realm.RealmConfiguration.<init>(Unknown Source)
at io.realm.RealmConfiguration.<init>(Unknown Source)
at io.realm.RealmConfiguration$Builder.build(Unknown Source)
at com.example.realm.RealmHelper.a(Unknown Source)
at com.example.activities.IntroActivity.onCreate(Unknown Source)
at android.app.Activity.performCreate(Activity.java:6251)
Not sure if that helps...

Answer 1

We were able to fix this by splitting out our two #RealmModule classes into separate files. I.e. we went from:
RealmHelper.java
#RealmModule(classes = {Publisher.class, Puzzle.class, Volume.class, VolumeSet.class})
public static class ManifestModule {
}
#RealmModule(classes = {PuzzleMove.class, PuzzleState.class, VolumeState.class})
public static class PuzzleStateModule {
}
to:
realm/modules/ManifestModule.java
#RealmModule(classes = {Publisher.class, Puzzle.class, Volume.class, VolumeSet.class})
public class ManifestModule {
}
and realm/modules/PuzzleStateModule.java
#RealmModule(classes = {PuzzleMove.class, PuzzleState.class, VolumeState.class})
public class PuzzleStateModule {
}
RealmHelper.java
import com.example.realm.modules.ManifestModule;
import com.example.realm.modules.PuzzleStateModule
I'm not sure what magic wasn't happening with one file that worked ok with two, and why Proguard nudged it one way or the other, but it seems to be working again!