Failed to resolve BluetoothLeScannerCompat when used through a library

[mmacagno]

Hello.
I built a JAR library to provide Bluetooth capabilities to our Android apps.

The build.gradle file of our library has the following declaration:

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar']
    coreLibraryDesugaring 'com.android.tools:desugar_jdk_libs:2.0.3'
    implementation 'androidx.appcompat:appcompat:1.6.1'
    api 'no.nordicsemi.android:dfu:2.3.0'
    api 'no.nordicsemi.android.support.v18:scanner:1.6.0'
}

the proguard file has:

-keep class no.nordicsemi.android.dfu.** { *; }
-keep class no.nordicsemi.android.support.** { *; }

I would expect to be able to use my library and underlying Nordic libraries.

The app using my library will not work, unless I also add the same 2 nordic libraries in its own build.gradle.

What am I missing?

java.lang.NoClassDefFoundError: Failed resolution of: Lno/nordicsemi/android/support/v18/scanner/BluetoothLeScannerCompat;   
   at io.sensoria.sdk.Scanner.lambda$start$9$io-sensoria-sdk-Scanner(Scanner.java:330)
   at io.sensoria.sdk.Scanner$$ExternalSyntheticLambda4.run(Unknown Source:2)
   at java.lang.Thread.run(Thread.java:1012)
   Caused by: java.lang.ClassNotFoundException: Didn't find class "no.nordicsemi.android.support.v18.scanner.BluetoothLeScannerCompat" on path: DexPathList[[zip file "/data/app/~~ar3vAE4BarZp-xIAFkR4Ag==/io.sensoria.configurator-qzGFJlQd4u-R3t4pvtMPIQ==/base.apk"],nativeLibraryDirectories=[/data/app/~~ar3vAE4BarZp-xIAFkR4Ag==/io.sensoria.configurator-qzGFJlQd4u-R3t4pvtMPIQ==/lib/arm64, /data/app/~~ar3vAE4BarZp-xIAFkR4Ag==/io.sensoria.configurator-qzGFJlQd4u-R3t4pvtMPIQ==/base.apk!/lib/arm64-v8a, /system/lib64, /system_ext/lib64, /product/lib64]]
   at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:259)
   at java.lang.ClassLoader.loadClass(ClassLoader.java:379)
   at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
   at io.sensoria.sdk.Scanner.lambda$start$9$io-sensoria-sdk-Scanner(Scanner.java:330) 
   at io.sensoria.sdk.Scanner$$ExternalSyntheticLambda4.run(Unknown Source:2) 
   at java.lang.Thread.run(Thread.java:1012)