@Override
    void createVendorMeshMessage(@NonNull final Message message) {
        if (message instanceof AccessMessage) {
            super.createVendorMeshMessage(message);
            createLowerTransportAccessPDU((AccessMessage) message);
        } else {
            createLowerTransportControlPDU((ControlMessage) message);
        }
    }
Creates the network layer pdu

@param message message with underlying data
@return Complete pdu message that is ready to be sent
mesh/src/main/java/no/nordicsemi/android/mesh/transport/LowerTransportLayer.java