code: public static String generate() {
          Random random = new SecureRandom();
          StringBuilder secret = new StringBuilder();
          for (int i = 1; i <= 64; i++) {
              secret.append((char) (random.nextInt(74) + 48));
          }
          String r = secret.toString().replaceAll("\\\\+", "/");
          if (r.length() != 64) {
              // It may happen if a non printable character is generated.
              return generate();
          }
          return r;
      }
docs: Generates a new application key.
  <p>
  <strong>Note:</strong> the generation is attempted several times if previous generation did not generate 64
  printable characters. Potentially, the generation may never ends, well, you would be really unlucky in that
  case.
  </p>
  
  @return the generated key.