ConcurrentDictionary AddOrUpdate a list

我正在尝试使用ConcurrentDictionary来帮助完成过滤任务。

如果列表中出现一个数字，那么我想将一个词条从一个字典复制到另一个字典。

但是AddOrUpdate的这一部分是不对的-v.Add(number)

我得到

"无法将类型'void'隐式转换为 'System.Collections.Generic.List'

还有两个错误。

class Program
{
    static void Main(string[] args)
    {
        Program p = new Program();
        List<int> filter = new List<int> {1,2};
        p.Filter(filter);
    }

    private void Filter(List<int> filter)
    {
        Dictionary<string, List<int>> unfilteredResults = new Dictionary<string, List<int>>();
        unfilteredResults.Add("key1", new List<int> { 1,2,3,4,5});
        ConcurrentDictionary<string, List<int>> filteredResults = new ConcurrentDictionary<string, List<int>>();
        foreach (KeyValuePair<string, List<int>> unfilteredResult in unfilteredResults)
        {
            foreach (int number in unfilteredResult.Value)
            {
                if (filter.Contains(number))
                {
                    filteredResults.AddOrUpdate(unfilteredResult.Key, new List<int> { number }, (k, v) => v.Add(number));
                }
            }
        }
    }
}