docs: static public X509Certificate readCertificate(String filename)
              throws Exception {
          InputStream inStream = null;
          X509Certificate cert = null;
          try {
              inStream = Config.getInstance().getInputStreamFromFile(filename);
              if (inStream != null) {
                  CertificateFactory cf = CertificateFactory.getInstance("X.509");
                  cert = (X509Certificate) cf.generateCertificate(inStream);
              } else {
                  logger.info("Certificate " + Encode.forJava(filename) + " not found.");
              }
          } catch (Exception e) {
              logger.error("Exception: ", e);
          } finally {
              if (inStream != null) {
                  try {
                      inStream.close();
                  } catch (IOException ioe) {
                      logger.error("Exception: ", ioe);
                  }
              }
          }
          return cert;
      }