public int getPeriod(){
        return calculateHeartbeatPeriod(periodLog);
    }
Heartbeat subscription.

@param dst         Destination address identifies the Heartbeat Publication
                   destination where the address can only be an unassigned address,
                   unicast address or a group address. All other values are prohibited.
@param countLog    Number of Heartbeat messages to be sent.
@param periodLog   Period for sending Heartbeat messages.
@param ttl         TTL to be used when sending Heartbeat messages.
@param features    Bit field indicating features that trigger Heartbeat messages when changed.
@param netKeyIndex Net key index.
mesh/src/main/java/no/nordicsemi/android/mesh/utils/HeartbeatPublication.java