code: @Override
      public Result check() {
          Result result = Result.newResult();
          for (FileEntry entry : entries) {
              if (entry.refresh(entry.getFile())) {
                  //check update only
                  result.addUpdatedFile(entry.getFile());
              }
          }
          return result;
      }
docs: /* (non-Javadoc)
  @see org.opoo.press.monitor.Observer#check()