if (equals(player) || !player.isOnline() || !session.isActive()) return;
if (hiddenEntities.contains(player.getUniqueId())) return;
hiddenEntities.add(player.getUniqueId());
if (knownEntities.remove(player)) {
session.send(new DestroyEntitiesMessage(Arrays.asList(player.getEntityId())));
}
session.send(UserListItemMessage.removeOne(player.getUniqueId()));
}