question: public static CacheSpan createCacheEntry ( File file ) { Matcher matcher = CACHE_FILE_PATTERN_V2 . matcher ( file . getName ( ) ) ; if ( ! matcher . matches ( ) ) { return null ; } String key = Util . unescapeFileName ( matcher . group ( 1 ) ) ; return key == null ? null : createCacheEntry ( key , Long . parseLong ( matcher . group ( 2 ) ) , Long . parseLong ( matcher . group ( 4 ) ) , file ) ; }
target:  Creates a cache span from an underlying cache file.