[jdom-interest] Javadoc suggestion for Element.java

[Jason Hunter]

> Here is a short text which I feel might be of use to programmers who
> might want to subclass Element.

I took your base and enhanced it a little.  Let me know if you think
anything needs to be added.  You're right this has the potential to
cause problems because a simple Element subclass constructor will
implicitly call super().  If this doesn't take care of people's
problems, we should add it to the FAQ.  Notice I removed your part about
"if you can't call a non-default" since it wasn't clear to me when that
might occur.  Perhaps you could explain.

    /**
     * <p>
     * This protected constructor is provided in order to support an
Element
     * subclass that wants full control over variable initialization. 
It
     * intentionally leaves all instance variables null, allowing a
     * lightweight subclass implementation.  The subclass is responsible
for
     * ensuring all the get and set methods on Element behave as
documented.
     * </p>
     *
     * <p>
     * When implementing an <code>Element</code> subclass which doesn't
     * require full control over variable initialization, be aware that
     * simply calling super() (or letting the compiler add the implicit
     * super() call) will not initialize the instance variables which
will
     * cause many of the methods to throw a
     * <code>{@link NullPointerException>}</code>.  Therefor, the
     * constructor for these subclasses should call one of the public
     * constructors so variable initialization is handled automatically.
     * </p>
     */

-jh-