code: public LastModified setLastModified(Date lastModified) {
  		LastModified prop = (lastModified == null) ? null : new LastModified(lastModified);
  		setLastModified(prop);
  		return prop;
  	}
docs: Sets the date-time that the journal entry was last changed.
  @param lastModified the last modified date or null to remove
  @return the property that was created
  @see <a href="http://tools.ietf.org/html/rfc5545#page-138">RFC 5545
  p.138</a>
  @see <a href="http://tools.ietf.org/html/rfc2445#page-131">RFC 2445
  p.131</a>