using System;

using System.Linq;

using System.Collections.Generic;

​

public class Asset

{

    public Guid DiscoveryId { get; set; }

    public string Foo { get; set; }

}

​

public class Device

{

    public Guid DeviceId { get; set; }

    public string Bar { get; set; }

}

​

public class Program

{

    public static void Main()

    {

        var devices = new List<Device>();

        var assets = new List<Asset>();

        for (int i = 0; i < 3; ++i)

        {

            var guid = Guid.NewGuid();

            assets.Add(new Asset { DiscoveryId = guid, Foo = i.ToString() });

            devices.Add(new Device { DeviceId = guid, Bar = (i*2).ToString() });

        }

        assets.Add(new Asset { DiscoveryId = Guid.NewGuid(), Foo = "Foo" });

        devices.Add(new Device { DeviceId = Guid.NewGuid(), Bar = "Bar" });

        Console.WriteLine("Assets:");

        foreach (var asset in assets) Console.WriteLine($"{asset.DiscoveryId}: {asset.Foo}");

        Console.WriteLine();

        Console.WriteLine("Devices:");

        foreach (var device in devices) Console.WriteLine($"{device.DeviceId}: {device.Bar}");

        Console.WriteLine();

        Console.WriteLine("Filtered:");

        var assetDevices = assets.Where(a => devices.Any(d => d.DeviceId == a.DiscoveryId));

        foreach (var asset in assetDevices) Console.WriteLine($"{asset.DiscoveryId}: {asset.Foo}");

        Console.WriteLine();

        var sameAssets = assets.Where(a => devices.Any(d => d.DeviceId == a.DiscoveryId));

        foreach (var asset in sameAssets)

        {

            var device = devices.SingleOrDefault(d => d.DeviceId == asset.DiscoveryId);

            if (device is null) continue;

            asset.Foo = device.Bar;

        }

        Console.WriteLine("Updated:");

        foreach (var asset in assetDevices) Console.WriteLine($"{asset.DiscoveryId}: {asset.Foo}");

        Console.WriteLine();

    }

}

​