"classes" not working on flow_from_dataframe?

[qinst64]

The parameter classes of flow_from_dataframe is working as above documentation
as the code dismisses order

        if classes:
            classes = set(classes)  # sort and prepare for membership lookup
            df[y_col] = df[y_col].apply(lambda x: remove_classes(x, classes))
        else:
            classes = set()
            for v in df[y_col]:
                if isinstance(v, (list, tuple)):
                    classes.update(v)
                else:
                    classes.add(v)
        return df.dropna(subset=[y_col]), sorted(classes)

Reproducible example: https://github.com/keras-team/keras/issues/13637

[rragundez]

The classes parameter is for the user to set which classes to use. If given in different order they still define the same classes to use, therefore the result should be the same. Do you think is the documentation which needs to change?