Shorten an UUIDv4 by encoding in Base64

UuidShortener.java

import java.util.UUID;
import java.util.Base64;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;

public class UuidShortener {

  /* NOTE:
   * The implementation was mostly copied from StackOverflow [1],
   * as well as the hint of using BIG_ENDIAN [2].
   *
   * [1]: https://stackoverflow.com/a/29836273/495558
   * [2]: https://stackoverflow.com/a/40297651/495558 
   */

  public static String shorten(UUID uuid) {
    ByteBuffer bb = ByteBuffer.allocate(16) // UUIDv4 is a 128-bit octet.
      .order(ByteOrder.BIG_ENDIAN) // UUID Standard uses big-endian for binary presentation.
      .putLong(uuid.getMostSignificantBits())
      .putLong(uuid.getLeastSignificantBits());

    return Base64.getUrlEncoder().withoutPadding().encodeToString(bb.array());
  }

  public static UUID restore(String shortenUuid) {
    byte[] octets = Base64.getUrlDecoder().decode(shortenUuid);
    ByteBuffer bb = ByteBuffer.wrap(octets);
    long mostSigBits = bb.getLong();
    long leastSigBits = bb.getLong();
    return new UUID(mostSigBits, leastSigBits);
  }
}