This can happen when some of the interface operations have added logic, but others (like Validate here) don't, so just get delegated as-is.
One typical example is a tower of wrapped streams, where each layer applies additional transformations to the streamed data, but the Close operation is just passed across all layers to the lowest one (which closes the underlying file or whatever).
One typical example is a tower of wrapped streams, where each layer applies additional transformations to the streamed data, but the Close operation is just passed across all layers to the lowest one (which closes the underlying file or whatever).