[Bug Report] TwinCollection.ClearMetadata does not clean metadata for properties

[florianbader]

Context

• OS, version, SKU and CPU architecture used: Win 10 Desktop x64 (Windows 10 Desktop x64, Ubuntu 15.04 x86, Windows 10 IoT Core arm32, etc.)
• Application's .NET Target Framework : .NET 5 (See https://docs.microsoft.com/en-us/dotnet/standard/frameworks. E.g. netcoreapp2.1, net451, uap10.0, xamarin)
• Device: : Laptop (Laptop, Raspberry PI3, Android APIv25 etc.)
• SDK version used: Microsoft.Azure.Devices 1.30.0 (Please include the NuGet package version for all involved components)

Description of the issue

Using the GetTwin method from RegistryManager returns the TwinProperties as TwinCollection. If using ClearMetadata on the TwinCollection for e.g. the desired properties it will not clear the metadata for the properties. Because of that if accessing a property afterwards it will return a TwinCollection instead of a JObject in the TryGetMemberInternal method. This is unexpected because after clearing the metadata I would expect a JObject which causes a RuntimeBindingException.

Code sample exhibiting the issue

var twin = await registryManager.GetTwinAsync("device");
twin.Properties.Desired.ClearMetadata();
twin.Properties.Desired["property"].GetType() // expected JObject, got TwinCollection

Current workaround which is really ugly is this:

var twin = await registryManager.GetTwinAsync("device");
twin.Properties.Desired.ClearMetadata();
var twinPatch = new Twin(new TwinProperties { Desired = new TwinCollection(twin.Properties.Desired.ToJson()) });
twin.Properties.Desired["property"].GetType() // returns JObject

[jamdavi]

Hey @florianbader,

I was able to reproduce the same behavior. I see a way around this by separating the metadata JObject from the payload JObject. Let me reach out to the team internally to see if there is any negative implications to doing this.

[jamdavi]

@florianbader We have added a new method called ClearAllMetadata this is a more extensive method that destroys the underlying metadata object and will have the desired effect you're looking for. I'll leave this issue open and update when we make a new release.

[abhipsaMisra]

This feature has been released in our latest release: https://github.com/Azure/azure-iot-sdk-csharp/releases/tag/2021-8-11
Closing this issue.