How to set warning message in custom CellFactory (ColumnRearranger)

I have a custom CellFactory (not anonymous) used in a ColumnRearranger. How can I set a warning messsage on the containing node if an issue occurs like missing cells -> no value calculated or an error in the input like invalid chemical structure?

You could extend from AbstractCellFactory and use the afterProcessing method?

If you want to use your own implementation you could pass in the NodeModel as reference in the constructor and then call setWarningMessage on it from your implementation of getCells().