Cleanup needed for SeriesBuffer.filleddata()

filleddata() seems to not be as useful as it should be. Here is its definition

def filleddata(self, zeros_func) -> Array:
        """Fill the data with zeros if buffer is a gap, otherwise return the data.

        Args:
            zeros_func:
                the function to produce a zeros array

        Returns:
            Array, the filled data
        """
        if self.data is not None:
            return self.data
        else:
            return zeros_func(self.shape)

My concerns are

1. Why does it need a zeros func instead of using the zerosfunc from its own backend?
2. Should it be a property so that it is more congruous with data?