https://github.com/datastax/csharp-driver/blob/786f3edae65f7726175394d650c900b7a2eda247/src/Cassandra/Mapping/Statements/StatementFactory.cs#L66-L70
GetOrAdd invokes the Func before any synchronization occurs. Potential solution is to implement this method on our CopyOnWriteDictionary (invoking the Func inside the lock).