question: public static String extractFileSetFromPath ( String resource ) { String [ ] splits = resource . split ( "[/]" ) ; if ( splits . length <= 3 ) { Stats . incr ( "invalid-resource" ) ; return null ; } return splits [ splits . length - 3 ] ; }
target:  Return the fileset corresponding to a file on HDFS. If the file path is not valid, then return null.