private void sendUpdate(UUID uniqueId) {
        this.plugin.getBootstrap().getScheduler().sync().execute(() -> {
            this.plugin.getBootstrap().getPlayer(uniqueId).ifPresent(player -> {
                MinecraftServer server = player.getServer();
                if (server != null) {
                    server.getPlayerList().sendPlayerPermissionLevel(player);
                }
            });
        });
    }
Calls {@link net.minecraft.server.players.PlayerList#sendPlayerPermissionLevel(ServerPlayer)} when a players permissions change.
forge/src/main/java/me/lucko/luckperms/forge/listeners/ForgeCommandListUpdater.java