code: public Chunk setUnderline(Color color, float thickness, float thicknessMul,
  			float yPosition, float yPositionMul, int cap) {
  		if (attributes == null)
  			attributes = new HashMap();
  		Object obj[] = {
  				color,
  				new float[] { thickness, thicknessMul, yPosition, yPositionMul, cap } };
  		Object unders[][] = Utilities.addToArray((Object[][]) attributes.get(UNDERLINE),
  				obj);
  		return setAttribute(UNDERLINE, unders);
  	}
docs: Sets an horizontal line that can be an underline or a strikethrough.
  Actually, the line can be anywhere vertically and has always the <CODE>
  Chunk</CODE> width. Multiple call to this method will produce multiple
  lines.
  
  @param color
  the color of the line or <CODE>null</CODE> to follow the
  text color
  @param thickness
  the absolute thickness of the line
  @param thicknessMul
  the thickness multiplication factor with the font size
  @param yPosition
  the absolute y position relative to the baseline
  @param yPositionMul
  the position multiplication factor with the font size
  @param cap
  the end line cap. Allowed values are
  PdfContentByte.LINE_CAP_BUTT, PdfContentByte.LINE_CAP_ROUND
  and PdfContentByte.LINE_CAP_PROJECTING_SQUARE
  @return this <CODE>Chunk</CODE>