code: private void drawXLabel(Graphics2D chartGraphics) {
      if (xAxisLabel != null) {
        // Strings are drawn from the baseline position of the leftmost char.
        int yPosXAxisLabel = chartSize.height - (margin / 2) - xAxisLabelDescent;
        // TODO This will need to be updated if the y-axis values/label can be moved to the right.
        int xPosXAxisLabel = heatMapC.x - (xAxisLabelSize.width / 2);
  
        chartGraphics.setFont(axisLabelsFont);
        chartGraphics.setColor(axisLabelColour);
        chartGraphics.drawString(xAxisLabel, xPosXAxisLabel, yPosXAxisLabel);
      }
    }
docs: /*
  Draws the x-axis label string if it is not null.