When trying to make a transaction on a boundContract with geth-api through the library of @karalabe . I am missing a way to get the signer. I only see the interface for signer in the aar but no way to get a implementation of it.

java.lang.RuntimeException: java.lang.reflect.InvocationTargetException at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120) Caused by: java.lang.reflect.InvocationTargetException at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120) Caused by: java.lang.Exception: no signer to authorize the transaction with at go.Seq.throwException(Seq.java:52) at org.ethereum.geth.BoundContract.transfer(Native Method) at org.ligi.ewallet.MainActivity$onCreate$function$1.invoke(MainActivity.kt:68) at org.ligi.ewallet.MainActivity$onCreate$function$1.invoke(MainActivity.kt:27) at org.ligi.ewallet.MainActivityKt$sam$OnClickListener$af810d58.onClick(MainActivity.kt:0) at android.view.View.performClick(View.java:5697) at android.view.View$PerformClick.run(View.java:22526) at android.os.Handler.handleCallback(Handler.java:739) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:158) at android.app.ActivityThread.main(ActivityThread.java:7225) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)