code: public void setPartialDate(final Integer day, final Integer month, final Integer year) {
  		// Validate Year
  		if (!isValidYear(year)) {
  			throw new IllegalArgumentException("Setting invalid partial year value (" + year
  					+ "). Year should be between " + YEAR_MIN + " to " + YEAR_MAX + ".");
  		}
  
  		// Validate Month
  		if (!isValidMonth(month)) {
  			throw new IllegalArgumentException("Setting invalid partial month value (" + month
  					+ "). Month should be between " + MONTH_MIN + " to " + MONTH_MAX + ".");
  		}
  
  		// Validate Day
  		if (!isValidDay(day)) {
  			throw new IllegalArgumentException("Setting invalid partial day value (" + day
  					+ "). Day should be between " + DAY_MIN + " to " + DAY_MAX + ".");
  		}
  
  		String formatted = formatPartialDateToString(day, month, year, getPaddingChar());
  
  		setData(formatted);
  		PartialDateFieldModel model = getOrCreateComponentModel();
  		model.text = null;
  		model.validDate = true;
  	}
docs: Set the WPartialDateField with the given day, month and year. Each of the day, month and year parameters that
  make up the partial date are optional.
  
  @param day A number from 1 to 31 or null if unknown.
  @param month A number from 1 to 12, or null if unknown.
  @param year A number, or null if unknown.