customproperties.addProperty("Test", 123); CTProperty ctproperty = customproperties.getProperty("Test"); System.out.println(ctproperty); System.out.println(ctproperty.getI4()); ctproperty = customproperties.getProperty("Test Date"); ctproperty.unsetI4(); ctproperty.setFiletime(new GregorianCalendar(2016,1,13)); ctproperty = customproperties.getProperty("Test Date"); System.out.println(ctproperty); System.out.println(ctproperty.getFiletime());