xamarinmac 
namespace System.DirectoryServices.ActiveDirectory
{
    public class AdamInstance : DirectoryServer
    {
        public override SyncUpdateCallback? SyncFromAllServersCallback { get; set; }
    }
}
.NET 5.06.07.08.09.010.0
.NET Core 2.02.12.23.03.1
.NET Framework 2.03.03.54.04.54.5.14.5.24.64.6.14.6.24.74.7.14.7.24.84.8.1
.NET Standard 2.02.1
Information specific to xamarinmac
Assembly

System.DirectoryServices , Version=4.0.0.0, PublicKeyToken=b03f5f7f11d50a3a

Referencing

Your project needs a package reference to System.DirectoryServices.

Package System.DirectoryServices (9.0.3) netstandard2.0
Platform Restrictions

The property getter is only supported on the following platforms:

  • Windows

The property setter is only supported on the following platforms:

  • Windows
  • Built-in API
  • Package-provided API