question: @ Nullable public static String md5 ( @ Nullable File file , @ Nullable IgniteLogger log ) { if ( file != null ) return file . isFile ( ) ? fileMd5 ( file , log ) : directoryMd5 ( file , log ) ; return null ; }
target:  Calculates md5 checksum for the given file o directory. For directories tries to walk all nested files accumulating the result.