<PackageReference Include="System.ObjectModel" Version="4.0.10-beta-23019" />

ReadOnlyDictionary<TKey, TValue>

public class ReadOnlyDictionary<TKey, TValue> : IDictionary<TKey, TValue>, ICollection<KeyValuePair<TKey, TValue>>, IEnumerable<KeyValuePair<TKey, TValue>>, IEnumerable, IDictionary, ICollection, IReadOnlyDictionary<TKey, TValue>, IReadOnlyCollection<KeyValuePair<TKey, TValue>>
public sealed class KeyCollection<TKey, TValue> : ICollection<TKey>, IEnumerable<TKey>, IEnumerable, ICollection, IReadOnlyCollection<TKey>

public sealed class ValueCollection<TKey, TValue> : ICollection<TValue>, IEnumerable<TValue>, IEnumerable, ICollection, IReadOnlyCollection<TValue>

public int Count { get; }

protected IDictionary<TKey, TValue> Dictionary { get; }

public TValue this[TKey key] { get; }

public KeyCollection<TKey, TValue> Keys { get; }

public ValueCollection<TKey, TValue> Values { get; }

public ReadOnlyDictionary(IDictionary<TKey, TValue> dictionary)

public bool ContainsKey(TKey key)

public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator()

public bool TryGetValue(TKey key, out TValue value)