DOMCategory: NullPointerException in setValue() when element has no text

NullPointerException at groovy.xml.dom.DOMCategory.setValue(DOMCategory.java:261) if setting value on element that has no text.

Example is to modify input in the example shown on the "Updating XML with DOMCategory" page (http://groovy.codehaus.org/Updating+XML+with+DOMCategory) to include an empty<item/> element, like this:

...
<category type="groceries">
<item>Chocolate</item>
<item>Coffee</item>
<item/>
</category>
...

This modification to input causes NullPointerException at this line in the
example:

g.value = 'Luxury ' + g.text()