Try this but check the IP adress method in your sources.
public static void AutoReward()
{
List<String> ips = new ArrayList<>();
Collection <L2PcInstance> pls = L2World.getInstance().getAllPlayers();
for (L2PcInstance p : pls)
{
final String ip = p.getConnection().getInetAddress();
if (ips.contains(ip))
continue;
p.sendMessage("AutoReward: You got " + Config.AUTO_REWARD_COUNT + " " + Config.NAME_ITEM_REWARD + " by being online");
p.getInventory().addItem("", Config.AUTO_REWARD_ID, Config.AUTO_REWARD_COUNT, p, null);
ips.add(ip);
}
}