code: public static String shortUuid() {
          // source: java.util.UUID.randomUUID()
          final byte[] randomBytes = new byte[16];
          UUID_GENERATOR.nextBytes(randomBytes);
          randomBytes[6] = (byte) (randomBytes[6] & 0x0f); // clear version
          randomBytes[6] = (byte) (randomBytes[6] | 0x40); // set to version 4
          randomBytes[8] = (byte) (randomBytes[8] & 0x3f); // clear variant
          randomBytes[8] = (byte) (randomBytes[8] | 0x80); // set to IETF variant
  
          // all base 64 encoding schemes use A-Z, a-z, and 0-9 for the first 62 characters. for the
          // last 2 characters, we use hyphen and underscore, which are URL safe
          return BaseEncoding.base64Url().omitPadding().encode(randomBytes);
      }
docs: Returns a short UUID which is encoding use base 64 characters instead of hexadecimal. This
  saves 10 bytes per UUID.
  
  @return short UUID which is encoding use base 64 characters instead of hexadecimal