namespace System.Net.Http.Headers
{
    [DefaultMember("Item")]
    public readonly struct HttpHeadersNonValidated : IEnumerable, IEnumerable<KeyValuePair<string!, HeaderStringValues>>, IReadOnlyCollection<KeyValuePair<string!, HeaderStringValues>>, IReadOnlyDictionary<string!, HeaderStringValues>
    {
        public bool Contains(string! headerName);
    }
}