<PackageReference Include="Microsoft.Bcl.AsyncInterfaces" Version="10.0.1" />

System.Runtime.InteropServices.LibraryImportAttribute

Attribute used to indicate a source generator should create a function for marshalling arguments instead of relying on the runtime to generate an equivalent marshalling function at run-time.
namespace System.Runtime.InteropServices { internal sealed class LibraryImportAttribute : Attribute { public string LibraryName { get; } public string EntryPoint { get; set; } public System.Runtime.InteropServices.StringMarshalling StringMarshalling { get; set; } public Type StringMarshallingCustomType { get; set; } public bool SetLastError { get; set; } public LibraryImportAttribute(string libraryName); } }