namespace Microsoft.AspNetCore.Http
{
    [DebuggerDisplay("{DebuggerToString(),nq}")]
    [DebuggerTypeProxy(typeof(StringValuesDictionaryDebugView))]
    [DefaultMember("Item")]
    public class HeaderDictionary : IHeaderDictionary, ICollection<KeyValuePair<string!, StringValues>>, IDictionary<string!, StringValues>, IEnumerable, IEnumerable<KeyValuePair<string!, StringValues>>
    {
        public bool ContainsKey(string! key);
    }
}