final int getTransportLayerSequenceNumber(final int networkLayerSequenceNumber, final int seqZero) {
        if ((networkLayerSequenceNumber & TRANSPORT_SAR_SEQZERO_MASK) < seqZero) {
            return ((networkLayerSequenceNumber - ((networkLayerSequenceNumber & TRANSPORT_SAR_SEQZERO_MASK) - seqZero) - (TRANSPORT_SAR_SEQZERO_MASK + 1)));
        } else {
            return ((networkLayerSequenceNumber - ((networkLayerSequenceNumber & TRANSPORT_SAR_SEQZERO_MASK) - seqZero)));
        }
    }
Derives the original transport layer sequence number from the network layer sequence number that was received with every segment

@param networkLayerSequenceNumber sequence number on network layer which is a part of the original pdu received
@param seqZero                    the lower 13 bits of the sequence number. This is a part of the lower transport pdu header and is the same value for all segments
@return original transport layer sequence number that was used to encrypt the transport layer pdu
mesh/src/main/java/no/nordicsemi/android/mesh/transport/UpperTransportLayer.java