java.util.Enumeration is a legacy interface from java 1.0.
There are couple of cycles which use it to iterate over collections. We can replace this manual cycle with enchanced-for, which is shorter and easier to read.

javax.naming.directory.BasicAttribute#toString

            boolean start = true;
            for (Enumeration<Object> e = values.elements(); e.hasMoreElements(); ) {
                if (!start)
                    answer.append(", ");
                answer.append(e.nextElement());
                start = false;
            }

javax.naming.directory.BasicAttributes#writeObject

        Enumeration<Attribute> attrEnum = attrs.elements();
        while (attrEnum.hasMoreElements()) {
            s.writeObject(attrEnum.nextElement());
        }