/**
     * Provides serialization support.
     *
     * @param stream  the output stream.
     *
     * @throws IOException  if there is an I/O error.
     */
    private void writeObject(ObjectOutputStream stream) throws IOException {
        stream.defaultWriteObject();

        SerialUtilities.writeShape(this.legendItemShape, stream);
        SerialUtilities.writePaint(this.seriesPaint, stream);
        SerialUtilities.writePaint(this.baseSeriesPaint, stream);
        SerialUtilities.writePaint(this.seriesOutlinePaint, stream);
        SerialUtilities.writePaint(this.baseSeriesOutlinePaint, stream);
        SerialUtilities.writeStroke(this.seriesOutlineStroke, stream);
        SerialUtilities.writeStroke(this.baseSeriesOutlineStroke, stream);
        SerialUtilities.writePaint(this.labelPaint, stream);
        SerialUtilities.writePaint(this.axisLinePaint, stream);
        SerialUtilities.writeStroke(this.axisLineStroke, stream);
    }