A Comment object Represents a comment like this example from the XML 1.0 spec:
<!--* N.B. some readers (notably JC) find the following
paragraph awkward and redundant. I agree it's logically redundant:
it *says* it is summarizing the logical implications of
matching the grammar, and that means by definition it's
logically redundant. I don't think it's rhetorically
redundant or unnecessary, though, so I'm keeping it. It
could however use some recasting when the editors are feeling
stronger. -MSM *-->
No children
JDOM checks the content to make sure it's legal (i.e. does not contain a double-hyphen)