code: protected void sendMembershipList(LocalGossipMember me, List<LocalGossipMember> memberList) {
      GossipService.LOGGER.debug("Send sendMembershipList() is called.");
      me.setHeartbeat(System.currentTimeMillis());
      LocalGossipMember member = selectPartner(memberList);
      if (member == null) {
        return;
      }
      try (DatagramSocket socket = new DatagramSocket()) {
        socket.setSoTimeout(gossipManager.getSettings().getGossipInterval());
        InetAddress dest = InetAddress.getByName(member.getHost());
        ActiveGossipMessage message = new ActiveGossipMessage();
        message.getMembers().add(convert(me));
        for (LocalGossipMember other : memberList) {
          message.getMembers().add(convert(other));
        }
        byte[] json_bytes = om.writeValueAsString(message).getBytes();
        int packet_length = json_bytes.length;
        if (packet_length < GossipManager.MAX_PACKET_SIZE) {
          byte[] buf = createBuffer(packet_length, json_bytes);
          DatagramPacket datagramPacket = new DatagramPacket(buf, buf.length, dest, member.getPort());
          socket.send(datagramPacket);
        } else {
          GossipService.LOGGER.error("The length of the to be send message is too large ("
                  + packet_length + " > " + GossipManager.MAX_PACKET_SIZE + ").");
        }
      } catch (IOException e1) {
        GossipService.LOGGER.warn(e1);
      }
    }
docs: Performs the sending of the membership list, after we have incremented our own heartbeat.