This is a single item on a simple page.
WARNING: this code should execute under oracle and mysql. Oracle treats "" as null,
and apparently stores null as "". To produce predictable results for the rest of the
code, we normalize some of the fields to "" if they are null. The problem is if we
write "", Oracle will read it as null, but our code expects it to come back as "".
Note that this code is called both to construct new items in our code and by hibernate
to build an object when reading from the database.
NOTE: Please don't add any more fields to this class. Instead, take a look at
the SimplePageItemAttribute system we have set up.