code: public void addBorder(int bordersToAdd, int borderStyle, float borderWidth, Color borderColor) {
          if((bordersToAdd & Rectangle.LEFT) == Rectangle.LEFT) {
              setBorder(RtfBorder.LEFT_BORDER, borderStyle, borderWidth, borderColor);
          }
          if((bordersToAdd & Rectangle.TOP) == Rectangle.TOP) {
              setBorder(RtfBorder.TOP_BORDER, borderStyle, borderWidth, borderColor);
          }
          if((bordersToAdd & Rectangle.RIGHT) == Rectangle.RIGHT) {
              setBorder(RtfBorder.RIGHT_BORDER, borderStyle, borderWidth, borderColor);
          }
          if((bordersToAdd & Rectangle.BOTTOM) == Rectangle.BOTTOM) {
              setBorder(RtfBorder.BOTTOM_BORDER, borderStyle, borderWidth, borderColor);
          }
          if((bordersToAdd & Rectangle.BOX) == Rectangle.BOX && this.borderType == RtfBorder.ROW_BORDER) {
              setBorder(RtfBorder.VERTICAL_BORDER, borderStyle, borderWidth, borderColor);
              setBorder(RtfBorder.HORIZONTAL_BORDER, borderStyle, borderWidth, borderColor);
          }
      }
docs: Adds borders to the RtfBorderGroup
  
  @param bordersToAdd The borders to add (Rectangle.LEFT, Rectangle.RIGHT, Rectangle.TOP, Rectangle.BOTTOM, Rectangle.BOX)
  @param borderStyle The style of border to add (from RtfBorder)
  @param borderWidth The border width to use
  @param borderColor The border color to use