The content is stored as a java.util.List
which contains 
  
One String (soon to be Text) object per text node
One Element object per child element
One Comment object per comment
One CDATA object per CDATA section (Text?)
One ProcessingInstruction object per processing instruction
Use the regular methods of java.util.List to
add, remove, and inspect the contents of an element
Since the methods of java.util.List expect to work
with Object objects, casting back to JDOM types
and String is frequent
Various utility methods mean you don't always have to work with the full list.
Attributes and namespaces are available as separate lists since these are not children.