code: private boolean isModified(ArtifactEntry entry, File file) {
          long fileLastModified = FileUtils.fileLastModified(file);
          long entryLastModified = entry.getLastModified();
  
          // File 100K  entry  10K  delta 90k  true   (entry is much older than the file)
          // File  10k  entry 100k  delta 90k  true   (file is much older than the entry)
          // File  10k  entry   9k  delta  1k  false  (entry is slightly older than the file)
          // File   9k  entry  10k  delta  1k  false  (file is slightly older than the entry)
          // File   9k  entry   9k  delta  0k  false  (file and entry are exactly the same age)
  
          return ( Math.abs(fileLastModified - entryLastModified) >= 1010L );
      }
docs: Tell if an entry is modified relative to a file.  That is if
  the last modified times are different.
  
  File last update times are accurate to about a second.  Allow
  the last modified times to match if they are that close.
  
  @param entry The entry to test.
  @param file The file to test.
  
  @return True or false telling if the last modified times of the
  file and entry are different.