BI1055 error is thrown for iOS Binding project after migrating to .NET6

[APopatanasov]

Steps to Reproduce

I am currently migrating our iOS Binding project to .NET6. One of the APIs I am binding is a protocol that inherits from the native UIScrollViewDelegate protocol. When I try to build the project the an error is thrown.

1. Open the attached project.
2. Try to build it: dotnet build Net6Binding.csproj

Expected Behavior

The binding should be built.

Actual Behavior

An error is thrown.

BTOUCH : error BI1055: bgen: Internal error: failed to convert type 'System.Runtime.Versioning.SupportedOSPlatformAttribute, System.Runtime, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. Please file a bug report (https://github.com/xamarin/xamarin-macios/issues/new) with a test case.

Environment

MacOS Big Sur 11.3.1
dotner version - 6.0.100-preview.4.21255.9

Build Logs

log.txt

Example Project (If Possible)

Net6Binding.zip

[spouliot]

Complete stack trace

        BTOUCH error BI1055: bgen: Internal error: failed to convert type 'System.Runtime.Versioning.SupportedOSPlatformAttribute, System.Runtime, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. Please file a bug report (https://github.com/xamarin/xamarin-macios/issues/new) with a test case. [/Users/poupou/Downloads/Net6Binding/Net6Binding/Net6Binding.csproj]
       at AttributeManager.ConvertType(Type type, ICustomAttributeProvider provider) in /Users/builder/azdo/_work/1/s/xamarin-macios/src/generator-attribute-manager.cs:line 206
       at AttributeManager.CreateAttributeInstance[T](CustomAttributeData attribute, ICustomAttributeProvider provider) in /Users/builder/azdo/_work/1/s/xamarin-macios/src/generator-attribute-manager.cs:line 299
       at AttributeManager.FilterAttributes[T](IList`1 attributes, ICustomAttributeProvider provider) in /Users/builder/azdo/_work/1/s/xamarin-macios/src/generator-attribute-manager.cs:line 390
       at AttributeManager.GetCustomAttributes[T](ICustomAttributeProvider provider) in /Users/builder/azdo/_work/1/s/xamarin-macios/src/generator-attribute-manager.cs:line 405
       at Generator.SelectProtocolMethods(Type type, Nullable`1 static, Nullable`1 required)+MoveNext() in /Users/builder/azdo/_work/1/s/xamarin-macios/src/generator.cs:line 5641
       at System.Collections.Generic.List`1.InsertRange(Int32 index, IEnumerable`1 collection)
       at System.Collections.Generic.List`1.AddRange(IEnumerable`1 collection)
       at Generator.GenerateProtocolTypes(Type type, String class_visibility, String TypeName, String protocol_name, ProtocolAttribute protocolAttribute) in /Users/builder/azdo/_work/1/s/xamarin-macios/src/generator.cs:line 5991
       at Generator.Generate(Type type) in /Users/builder/azdo/_work/1/s/xamarin-macios/src/generator.cs:line 6411
       at Generator.Go() in /Users/builder/azdo/_work/1/s/xamarin-macios/src/generator.cs:line 2502
       at BindingTouch.Main3(String[] args) in /Users/builder/azdo/_work/1/s/xamarin-macios/src/btouch.cs:line 599
       at BindingTouch.Main2(String[] args) in /Users/builder/azdo/_work/1/s/xamarin-macios/src/btouch.cs:line 223
       at BindingTouch.Main(String[] args) in /Users/builder/azdo/_work/1/s/xamarin-macios/src/btouch.cs:line 89