code: private void addWeekNumberLabels() {
          weekNumberLabels = new ArrayList<JLabel>();
          int weekNumberLabelColumnX = constantFirstWeekNumberLabelCell.x;
          int weekNumberLabelWidthInCells = 1;
          int weekNumberLabelHeightInCells = 1;
          for (int i = 0; i < 6; ++i) {
              int weekNumberLabelRowY = (i + constantFirstWeekNumberLabelCell.y);
              JLabel weekNumberLabel = new JLabel();
              weekNumberLabel.setHorizontalAlignment(SwingConstants.CENTER);
              weekNumberLabel.setVerticalAlignment(SwingConstants.CENTER);
              weekNumberLabel.setBorder(new EmptyBorder(constantWeekNumberLabelInsets));
              weekNumberLabel.setOpaque(true);
              weekNumberLabel.setText("3" + i);
              weekNumberLabel.setVisible(false);
              CellConstraints constraints = CC.xywh(weekNumberLabelColumnX, weekNumberLabelRowY,
                  weekNumberLabelWidthInCells, weekNumberLabelHeightInCells);
              centerPanel.add(weekNumberLabel, constraints);
              weekNumberLabels.add(weekNumberLabel);
          }
          setSizeOfWeekNumberLabels();
      }
docs: addWeekNumberLabels, This adds a set of 6 week number labels to the calendar panel. The text
  of these labels is set with locale sensitive week numbers each time that the calendar is
  redrawn.
  
  This function should not depend on any settings variables.