Filename filter that accept filenames and extensions only created by Lucene.
Returns true if this is a file that would be contained in a CFS file.
|From class java.lang.Object|
|From interface java.io.FilenameFilter|
Returns true if this is a file that would be contained in a CFS file. This function should only be called on files that pass the above "accept" (ie, are already known to be a Lucene index file).