namespace System.Text.Json.Nodes
{
    public sealed class JsonObject : JsonNode, ICollection<KeyValuePair<string!, JsonNode?>>, IDictionary<string!, JsonNode?>, IEnumerable, IEnumerable<KeyValuePair<string!, JsonNode?>>, IList<KeyValuePair<string!, JsonNode?>>
    {
        public int IndexOf(string! propertyName);
    }
}