https://learn.microsoft.com/en-us/dotnet/api/system.collections.concurrent.concurrentdictionary-2.tryupdate?view=netframework-4.8.1&viewFallbackFrom=netcore-3.1
ConcurrentDictionaryTKey,TValue.TryUpdate(TKey, TValue, TValue) Method...
Updates the value associated with key to newValue if the existing value with key is equal to comparisonValue.
tkeymethod