Adding a *.jar file (originating from java-wrapped C++ code)  to an SBT project classpath

I thought using unmanaged dependencies in SBT projects was simply dropping a jar file
into the  lib directory, until I bought an SDK for a biometric device.

Both the C++ and the Java packages were provided. I opted for the Java package, copying the provided jar file and the JNI  (*.so) files into the appropriate locations and configuring the java.library.path property as appropriate.

I dropped a copy of the jar file into my lib directory; but I had compilation errors starting right from the import statement. All attempts failed, as long as I treated the jar file as an unmanaged dependency

I found the answer in installing it a managed dependency.

Below is my own humble code: