code: private String certificationRequestToPEM(PKCS10CertificationRequest csr) throws IOException {
          PemObject pemCSR = new PemObject("CERTIFICATE REQUEST", csr.getEncoded());
  
          StringWriter str = new StringWriter();
          JcaPEMWriter pemWriter = new JcaPEMWriter(str);
          pemWriter.writeObject(pemCSR);
          pemWriter.close();
          str.close();
          return str.toString();
      }
docs: certificationRequestToPEM - Convert a PKCS10CertificationRequest to PEM
  format.
  
  @param csr The Certificate to convert
  @return An equivalent PEM format certificate.
  @throws IOException