#if !NETSTANDARD2_1
using System;

/*https://github.com/i3arnon/ConcurrentHashSet*/

namespace ZeroLevel.Models
{
    namespace System.Diagnostics.CodeAnalysis
    {
        /// <summary>Specifies that when a method returns <see cref="ReturnValue"/>, the parameter may be null even if the corresponding type disallows it.</summary>
        [AttributeUsage(AttributeTargets.Parameter)]
        internal sealed class MaybeNullWhenAttribute : Attribute
        {
            /// <summary>Initializes the attribute with the specified return value condition.</summary>
            /// <param name="returnValue">
            /// The return value condition. If the method returns this value, the associated parameter may be null.
            /// </param>
            public MaybeNullWhenAttribute(bool returnValue) => ReturnValue = returnValue;

            /// <summary>Gets the return value condition.</summary>
            public bool ReturnValue { get; }
        }
    }
}
#endif