DictionaryExtensions.cs

    public static class DictionaryExtension
    {
        public static TValue GetValueOrDefault<TKey, TValue>(this Dictionary<TKey, TValue> dictionary, TKey key) where TValue : class
        {
            TValue value;
            return dictionary.TryGetValue(key, out value)
                ? value
                : default(TValue);
        }
    }