code: public ProductId setProductId(String prodId) {
  		ProductId property = (prodId == null) ? null : new ProductId(prodId);
  		setProductId(property);
  		return property;
  	}
docs: Sets the application that created the iCalendar object. All
  {@link ICalendar} objects are initialized with a product ID representing
  this library.
  @param prodId a unique string representing the application (e.g.
  "-//Company//Application//EN") or null to remove
  @return the property that was created
  @see <a href="http://tools.ietf.org/html/rfc5545#page-78">RFC 5545
  p.78-9</a>
  @see <a href="http://tools.ietf.org/html/rfc2445#page-75">RFC 2445
  p.75-6</a>
  @see <a href="http://www.imc.org/pdi/vcal-10.doc">vCal 1.0 p.24</a>