<PackageReference Include="NETStandard.Library" Version="2.0.0-preview2-25401-01" />

System.Collections.Generic.ICollection<T>

public interface ICollection<T> : IEnumerable<T>, IEnumerable
namespace System.Collections.Generic { public interface ICollection<T> : IEnumerable<T>, IEnumerable { int Count { get; } bool IsReadOnly { get; } void Add(T item); void Clear(); bool Contains(T item); void CopyTo(T[] array, int arrayIndex); bool Remove(T item); } }