<PackageReference Include="Microsoft.Bcl.AsyncInterfaces" Version="9.0.5" />

AsyncIteratorStateMachineAttribute

Indicates whether a method is an asynchronous iterator.
namespace System.Runtime.CompilerServices { [AttributeUsage(AttributeTargets.Method, Inherited = false, AllowMultiple = false)] public sealed class AsyncIteratorStateMachineAttribute : StateMachineAttribute { [System.Runtime.CompilerServices.NullableContext(1)] public AsyncIteratorStateMachineAttribute(Type stateMachineType) : base(stateMachineType) { } } }