code: @RequirePOST
      public void doDoFingerprintCheck( StaplerRequest req, StaplerResponse rsp ) throws IOException, ServletException {
          // Parse the request
          try (MultipartFormDataParser p = new MultipartFormDataParser(req)) {
              if (isUseCrumbs() && !getCrumbIssuer().validateCrumb(req, p)) {
                  // TODO investigate whether this check can be removed
                  rsp.sendError(HttpServletResponse.SC_FORBIDDEN, "No crumb found");
              }
              rsp.sendRedirect2(req.getContextPath()+"/fingerprint/"+
                  Util.getDigestOf(p.getFileItem("name").getInputStream())+'/');
          }
      }
docs: Do a finger-print check.