When I try to run HighFreqTerms.java in Lucene Revision: 933722  I get the the exception appended below.  I believe the line of code involved is a result of the flex indexing merge. Should I post this as a comment to LUCENE-2370 (Reintegrate flex branch into trunk)?
 
Or is there simply something wrong with my configuration?
 
Exception in thread "main" java.lang.UnsupportedOperationException: please use MultiFields.getFields if you really need a top level Fields (NOTE that it's usually better to work per segment instead)
        at org.apache.lucene.index.DirectoryReader.fields(DirectoryReader.java:762)
        at org.apache.lucene.misc.HighFreqTerms.main(HighFreqTerms.java:71)
 
Tom Burton-West