code: @Deprecated
      public X509Certificate loadDERCertificate(String filePath) throws IOException, CertificateException {
          try (InputStream certificateInputStream = CertUtils.toInputStream(filePath)) {
              return loadDERCertificate(certificateInputStream);
          }
      }
docs: Load certificate file in DER format from the filesystem or the classpath
  
  @param filePath
  Path to the file, containing the certificate.
  @return Loaded certificate.
  @throws IOException
  @throws CertificateException
  @deprecated