code: private static byte[] secureRandom(int size) {
          if (size <= 0)
              throw new IllegalArgumentException("Size cannot be zero or less than zero.");
  
          SecureRandom secureRandom = new SecureRandom();
          byte[] bytes = new byte[size];
          secureRandom.nextBytes(bytes);
          return bytes;
      }
docs: Secure random bytes of size in bytes
  @param size Size in bytes
  @return Random bytes