I have discusses this in past on mailing list, that Utility, helper, worker classes which contains only static methods should not be instantiable. Also we can restrict it by adding a private constructor.
Currently OFBiz has many such classes which should have private constructor. Identify all the *Worker.java, *.Helper.java, and *Util.java which do not have any non static method/member are eligible for having a private constructor.
Reference why we should do this : http://www.informit.com/articles/article.aspx?p=1216151&seqNum=4