<PackageReference Include="NETStandard.Library" Version="2.0.1" />

System.Security.Cryptography.X509Certificates.X509ExtensionCollection

namespace System.Security.Cryptography.X509Certificates { public sealed class X509ExtensionCollection : ICollection, IEnumerable { public int Count { get; } public bool IsSynchronized { get; } public X509Extension this[int index] { get; } public X509Extension this[string oid] { get; } public object SyncRoot { get; } public X509ExtensionCollection(); public int Add(X509Extension extension); public void CopyTo(X509Extension[] array, int index); public X509ExtensionEnumerator GetEnumerator(); } }