@Test
 public void testImmutableDate() {
   Date now = new Date();
   TransactionStoppedEvent event =
       new TransactionStoppedEvent(
           CHARGING_STATION_ID,
           TRANSACTION_ID,
           IDENTIFYING_TOKEN,
           METER_STOP,
           now,
           NULL_USER_IDENTITY_CONTEXT);
   event.getTimestamp().setTime(TWO_MINUTES_AGO.getTime());
   assertEquals(now, event.getTimestamp());
 }
  @Test
  public void constructorSetsFields() {
    TransactionStoppedEvent event =
        new TransactionStoppedEvent(
            CHARGING_STATION_ID,
            TRANSACTION_ID,
            IDENTIFYING_TOKEN,
            METER_STOP,
            FIVE_MINUTES_AGO,
            NULL_USER_IDENTITY_CONTEXT);

    assertEquals(CHARGING_STATION_ID, event.getChargingStationId());
    assertEquals(TRANSACTION_ID, event.getTransactionId());
    assertEquals(IDENTIFYING_TOKEN, event.getIdTag());
    assertEquals(METER_STOP, event.getMeterStop());
    assertEquals(FIVE_MINUTES_AGO, event.getTimestamp());
    assertEquals(NULL_USER_IDENTITY_CONTEXT, event.getIdentityContext());
  }