code: public Comment addComment(String comment) {
  		Comment prop = new Comment(comment);
  		addComment(prop);
  		return prop;
  	}
docs: Adds a comment to the journal entry.
  @param comment the comment to add
  @return the property that was created
  @see <a href="http://tools.ietf.org/html/rfc5545#page-83">RFC 5545
  p.83-4</a>
  @see <a href="http://tools.ietf.org/html/rfc2445#page-80">RFC 2445
  p.80-1</a>