In the current version of the library (v2.6.19.0), we have following cast:

BluetoothLEManager(Context context) {
    this.scannerEventsCallback = (IDcsScannerEventsOnReLaunch)context;

which immediately leads to a crash unless the context implements this interface.

What's the reason for this? Why cannot any class implement this interface and I can specify this as parameter or in an own method?

Previous versions of the library didn't have this restriction!?