.NET中是否有只读通用字典？

using System;
using System.Collections.Generic;

class Program
{
    static void Main(string[] args)
    {
        Dictionary<string, string> dictionary = new Dictionary<string, string>
        {
            { "key1", "value1" },
            { "key2", "value2" },
            { "key3", "value3" }
        };

        IReadOnlyDictionary<string, string> readOnlyDictionary = new ReadOnlyDictionary<string, string>(dictionary);

        foreach (var key in readOnlyDictionary.Keys)
        {
            Console.WriteLine($"{key}: {readOnlyDictionary[key]}");
        }
    }
}