https://learn.microsoft.com/zh-cn/dotnet/api/system.collections.generic.ireadonlydictionary-2.containskey?view=netframework-4.8.1&viewFallbackFrom=netcore-1.1
IReadOnlyDictionaryTKey,TValue.ContainsKey(TKey) Method (System.Collections.Generic) | Microsoft...
Determines whether the read-only dictionary contains an element that has the specified key.
tkeymethodsystemcollectionsgeneric