code: public RelatedTo addRelatedTo(String uid) {
  		RelatedTo prop = new RelatedTo(uid);
  		addRelatedTo(prop);
  		return prop;
  	}
docs: Adds a component that the journal entry is related to.
  @param uid the UID of the other component
  @return the property that was created
  @see <a href="http://tools.ietf.org/html/rfc5545#page-115">RFC 5545
  p.115-6</a>
  @see <a href="http://tools.ietf.org/html/rfc2445#page-109-10">RFC 2445
  p.109-10</a>