private void requestUpdate(UUID uniqueId) {
        if (!this.plugin.getBootstrap().isPlayerOnline(uniqueId)) {
            return;
        }

        // Buffer the request to send a commands update.
        SendBuffer sendBuffer = this.sendingBuffers.get(uniqueId);
        if (sendBuffer != null) {
            sendBuffer.request();
        }
    }
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