code: public static String getOriginalFileName(Part part) {
      String contentDisposition = part.getHeader("content-disposition");
      if (contentDisposition != null) {
        for (String cd : contentDisposition.split(";")) {
  
          if (cd.trim().startsWith("filename")) {
            String path = cd.substring(cd.indexOf('=') + 1).replaceAll("\"", "").trim();
            Path filename = Paths.get(path).getFileName();
            return StringUtils.hasText(filename.toString()) ? filename.toString() : null;
          }
        }
      }
  
      return null;
    }
docs: Get the filename of an uploaded file
  
  @return the filename or null if not present