How to select nodes that do NOT have a given child in JackRabbit

[Shane O'Sullivan]

I need to be able to run an XPATH query on jackrabbit that will allow me to
select all nodes that do not have a particular child.

For example, given the tree

<A>
   <B>
</A>
<A>
   <C>
</A>

I want to only select the "A" nodes that don't have a <B> child.
With Xpath I should be able to do something like
   /A/*[name()!='B']
or
   /A/*[count(B)=0]

but JackRabbit says that both of these XPath functions are not supported.
Does anyone know of another way to do this?

Thanks,

Shane