C#有办法给我一个不可变的字典吗？

using System.Collections.Generic;
using System.Collections.ObjectModel;

public class ImmutableDictionary<TKey, TValue>
{
    private readonly IDictionary<TKey, TValue> _dictionary;

    public ImmutableDictionary()
    {
        _dictionary = new Dictionary<TKey, TValue>();
    }

    public ImmutableDictionary(IDictionary<TKey, TValue> dictionary)
    {
        _dictionary = new ReadOnlyDictionary<TKey, TValue>(dictionary);
    }

    public TValue this[TKey key] => _dictionary[key];

    public bool ContainsKey(TKey key) => _dictionary.ContainsKey(key);

    public bool TryGetValue(TKey key, out TValue value) => _dictionary.TryGetValue(key, out value);

    public ImmutableDictionary<TKey, TValue> Add(TKey key, TValue value)
    {
        var newDictionary = new Dictionary<TKey, TValue>(_dictionary);
        newDictionary.Add(key, value);
        return new ImmutableDictionary<TKey, TValue>(newDictionary);
    }

    public ImmutableDictionary<TKey, TValue> Remove(TKey key)
    {
        var newDictionary = new Dictionary<TKey, TValue>(_dictionary);
        newDictionary.Remove(key);
        return new ImmutableDictionary<TKey, TValue>(newDictionary);
    }
}