code: public static TransactionId createTransactionId(String transactionNumber, ChargingStationId chargingStationId, String protocol) {
          return Ints.tryParse(checkNotNull(transactionNumber)) != null
                  ? new NumberedTransactionId(chargingStationId, protocol, Ints.tryParse(transactionNumber))
                  : new UuidTransactionId(UUID.fromString(transactionNumber));
      }
docs: Creates {@code NumberedTransactionId} or {@code UUIDTransactionId} by inspecting the provided transactionId String.
  @param transactionNumber     the String to create into a TransactionId
  @param chargingStationId     the chargingstation id
  @param protocol              the protocol identifier
  @return a {@code TransactionId}
  @throws NullPointerException in case transactionNumber is null.
  @throws IllegalArgumentException in case no {@code TransactionId} could be created.