Bug in {jiraissues} macro regarding sorting of results by JIRA

Using the macro:

{jiraissues:url=http://devapp:8081/secure/IssueNavigator.jspa?view=rss&sorter/field=priority&sorter/order=DESC&pid=10020&tempMax=10&resolution=-1&reset=true&decorator=none&os_username=guest&os_password=guest}

causes an exception:
Cause:
java.lang.reflect.InvocationTargetException
at sun.reflect.GeneratedMethodAccessor516.invoke(Unknown Source)

As far as I can tell, this is down to the 'sorter/field' parameter, containing a slash. I've tried replacing it with the URL encoded value of %2F and even %252f, but it makes no difference.