https://mongodb.github.io/mongo-csharp-driver/2.15/apidocs/html/Overload_MongoDB_Driver_UpdateDefinitionExtensions_SetOnInsert.htm
UpdateDefinitionExtensions.SetOnInsert Method
method
https://mongodb.github.io/mongo-csharp-driver/2.7/apidocs/html/Overload_MongoDB_Driver_UpdateDefinitionExtensions_SetOnInsert.htm
UpdateDefinitionExtensions.SetOnInsert Method
method