Program: 169340
Project: 169340
Buggy source:
public Component getTableCellRendererComponent(JTable table,Object value,boolean isSelected,boolean hasFocus,int row,int column){
  JLabel label=(JLabel)super.getTableCellRendererComponent(table,value,isSelected,hasFocus,row,column);
  label.setHorizontalAlignment(JLabel.CENTER);
  if (row == -1) {
    label.setForeground(getColors().getColor(ComponentColorDefaults.Key.FG_GRID_HEADER));
    label.setBackground(getColors().getColor(ComponentColorDefaults.Key.BG_GRID_HEADER));
    label.setHorizontalAlignment(JLabel.CENTER);
    return label;
  }
  Calendar todayCal=Calendar.getInstance();
  Calendar selectedCal=Calendar.getInstance();
  selectedCal.set(internalModel.getModel().getYear(),internalModel.getModel().getMonth(),internalModel.getModel().getDay());
  int cellDayValue=(Integer)value;
  int lastDayOfMonth=selectedCal.getActualMaximum(Calendar.DAY_OF_MONTH);
  if (cellDayValue < 1 || cellDayValue > lastDayOfMonth) {
    label.setForeground(getColors().getColor(ComponentColorDefaults.Key.FG_GRID_OTHER_MONTH));
    Calendar calForDay=Calendar.getInstance();
    calForDay.set(internalModel.getModel().getYear(),internalModel.getModel().getMonth(),cellDayValue);
    DateModel<Calendar> modelForDay=new UtilCalendarModel(calForDay);
    label.setBackground(checkConstraints(modelForDay) ? getColors().getColor(ComponentColorDefaults.Key.BG_GRID) : getColors().getColor(ComponentColorDefaults.Key.BG_GRID_NOT_SELECTABLE));
    if (cellDayValue > lastDayOfMonth) {
      label.setText(Integer.toString(cellDayValue - lastDayOfMonth));
    }
 else {
      Calendar lastMonth=new GregorianCalendar();
      lastMonth.set(selectedCal.get(Calendar.YEAR),selectedCal.get(Calendar.MONTH) - 1,1);
      int lastDayLastMonth=lastMonth.getActualMaximum(Calendar.DAY_OF_MONTH);
      label.setText(Integer.toString(lastDayLastMonth + cellDayValue));
    }
  }
 else {
    label.setForeground(getColors().getColor(ComponentColorDefaults.Key.FG_GRID_THIS_MONTH));
    Calendar calForDay=Calendar.getInstance();
    calForDay.set(internalModel.getModel().getYear(),internalModel.getModel().getMonth(),cellDayValue);
    DateModel<Calendar> modelForDay=new UtilCalendarModel(calForDay);
    label.setBackground(checkConstraints(modelForDay) ? getColors().getColor(ComponentColorDefaults.Key.BG_GRID) : getColors().getColor(ComponentColorDefaults.Key.BG_GRID_NOT_SELECTABLE));
    if (todayCal.get(Calendar.DATE) == cellDayValue && todayCal.get(Calendar.MONTH) == internalModel.getModel().getMonth() && todayCal.get(Calendar.YEAR) == internalModel.getModel().getYear()) {
      label.setForeground(getColors().getColor(ComponentColorDefaults.Key.FG_GRID_TODAY));
      if (internalModel.getModel().isSelected() && selectedCal.get(Calendar.DATE) == cellDayValue) {
        label.setForeground(getColors().getColor(ComponentColorDefaults.Key.FG_GRID_TODAY_SELECTED));
        label.setBackground(getColors().getColor(ComponentColorDefaults.Key.BG_GRID_TODAY_SELECTED));
      }
    }
 else {
      if (internalModel.getModel().isSelected() && selectedCal.get(Calendar.DATE) == cellDayValue) {
        label.setForeground(getColors().getColor(ComponentColorDefaults.Key.FG_GRID_SELECTED));
        label.setBackground(getColors().getColor(ComponentColorDefaults.Key.BG_GRID_SELECTED));
      }
    }
  }
  return label;
}

Fixed version (ground truth):
public Component getTableCellRendererComponent(JTable table,Object value,boolean isSelected,boolean hasFocus,int row,int column){
  if (value == null) {
    return super.getTableCellRendererComponent(table,value,isSelected,hasFocus,row,column);
  }
  JLabel label=(JLabel)super.getTableCellRendererComponent(table,value,isSelected,hasFocus,row,column);
  label.setHorizontalAlignment(JLabel.CENTER);
  if (row == -1) {
    label.setForeground(getColors().getColor(ComponentColorDefaults.Key.FG_GRID_HEADER));
    label.setBackground(getColors().getColor(ComponentColorDefaults.Key.BG_GRID_HEADER));
    label.setHorizontalAlignment(JLabel.CENTER);
    return label;
  }
  Calendar todayCal=Calendar.getInstance();
  Calendar selectedCal=Calendar.getInstance();
  selectedCal.set(internalModel.getModel().getYear(),internalModel.getModel().getMonth(),internalModel.getModel().getDay());
  int cellDayValue=(Integer)value;
  int lastDayOfMonth=selectedCal.getActualMaximum(Calendar.DAY_OF_MONTH);
  if (cellDayValue < 1 || cellDayValue > lastDayOfMonth) {
    label.setForeground(getColors().getColor(ComponentColorDefaults.Key.FG_GRID_OTHER_MONTH));
    Calendar calForDay=Calendar.getInstance();
    calForDay.set(internalModel.getModel().getYear(),internalModel.getModel().getMonth(),cellDayValue);
    DateModel<Calendar> modelForDay=new UtilCalendarModel(calForDay);
    label.setBackground(checkConstraints(modelForDay) ? getColors().getColor(ComponentColorDefaults.Key.BG_GRID) : getColors().getColor(ComponentColorDefaults.Key.BG_GRID_NOT_SELECTABLE));
    if (cellDayValue > lastDayOfMonth) {
      label.setText(Integer.toString(cellDayValue - lastDayOfMonth));
    }
 else {
      Calendar lastMonth=new GregorianCalendar();
      lastMonth.set(selectedCal.get(Calendar.YEAR),selectedCal.get(Calendar.MONTH) - 1,1);
      int lastDayLastMonth=lastMonth.getActualMaximum(Calendar.DAY_OF_MONTH);
      label.setText(Integer.toString(lastDayLastMonth + cellDayValue));
    }
  }
 else {
    label.setForeground(getColors().getColor(ComponentColorDefaults.Key.FG_GRID_THIS_MONTH));
    Calendar calForDay=Calendar.getInstance();
    calForDay.set(internalModel.getModel().getYear(),internalModel.getModel().getMonth(),cellDayValue);
    DateModel<Calendar> modelForDay=new UtilCalendarModel(calForDay);
    label.setBackground(checkConstraints(modelForDay) ? getColors().getColor(ComponentColorDefaults.Key.BG_GRID) : getColors().getColor(ComponentColorDefaults.Key.BG_GRID_NOT_SELECTABLE));
    if (todayCal.get(Calendar.DATE) == cellDayValue && todayCal.get(Calendar.MONTH) == internalModel.getModel().getMonth() && todayCal.get(Calendar.YEAR) == internalModel.getModel().getYear()) {
      label.setForeground(getColors().getColor(ComponentColorDefaults.Key.FG_GRID_TODAY));
      if (internalModel.getModel().isSelected() && selectedCal.get(Calendar.DATE) == cellDayValue) {
        label.setForeground(getColors().getColor(ComponentColorDefaults.Key.FG_GRID_TODAY_SELECTED));
        label.setBackground(getColors().getColor(ComponentColorDefaults.Key.BG_GRID_TODAY_SELECTED));
      }
    }
 else {
      if (internalModel.getModel().isSelected() && selectedCal.get(Calendar.DATE) == cellDayValue) {
        label.setForeground(getColors().getColor(ComponentColorDefaults.Key.FG_GRID_SELECTED));
        label.setBackground(getColors().getColor(ComponentColorDefaults.Key.BG_GRID_SELECTED));
      }
    }
  }
  return label;
}