After doing some further testing, I found that
<s:updownselect
list="courseList"
name="nonsenseName"
listKey="uuid" listValue="displayName"/>
works, but
<s:updownselect
list="courseList"
name="selectedCourses"
listKey="uuid" listValue="displayName"/>
Does not. selectedCourses is a String array on my action object, and before
this issue popped up, I was using OGNL to autopopulate the array with the
selected ids from courseList.
Now, every variation on "selectedCourses" raises this error.
(I've tried
selectedCourses
'selectedCourses'
%{selectedCourses}
%{'selectedCourses'}
so far).
-Brian