code: private float getBorderWidthInside(int side) {
          float width = 0f;
          if (useBorderPadding) {
              switch (side) {
                  case Rectangle.LEFT:
                      width = getBorderWidthLeft();
                      break;
  
                  case Rectangle.RIGHT:
                      width = getBorderWidthRight();
                      break;
  
                  case Rectangle.TOP:
                      width = getBorderWidthTop();
                      break;
  
                  default:    // default and BOTTOM
                      width = getBorderWidthBottom();
                      break;
              }
              // non-variable (original style) borders overlap the rectangle (only 1/2 counts)
              if (!isUseVariableBorders()) {
                  width = width / 2f;
              }
          }
          return width;
      }
docs: Gets the amount of the border for the specified side that is inside the Rectangle.
  For non-variable width borders this is only 1/2 the border width on that side.  This
  always returns 0 if {@link #useBorderPadding} is false;
  @param side the side to check.  One of the side constants in {@link com.lowagie.text.Rectangle}
  @return the borderwidth inside the cell