ProtectedConfigurationProviderCollection.cs

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Configuration.Provider;

namespace System.Configuration
{
    public class ProtectedConfigurationProviderCollection : ProviderCollection
    {
        public new ProtectedConfigurationProvider this[string name] => (ProtectedConfigurationProvider)base[name];

        public override void Add(ProviderBase provider)
        {
            if (provider is null)
            {
                throw new ArgumentNullException(nameof(provider));
            }

            if (!(provider is ProtectedConfigurationProvider))
            {
                throw new ArgumentException(
                    SR.Format(SR.Config_provider_must_implement_type,
                        typeof(ProtectedConfigurationProvider).ToString()), nameof(provider));
            }

            base.Add(provider);
        }
    }
}