### Question:
JodaDateTimeConverter implements Converter<Timestamp, DateTime> { @Override public Timestamp to(DateTime dateTime) { return dateTime != null ? new Timestamp(dateTime.getMillis()) : null; }  @Override DateTime from(Timestamp timestamp); @Override Timestamp to(DateTime dateTime); @Override Class<Timestamp> fromType(); @Override Class<DateTime> toType();  }### Answer:
@Test public void nullDateTimeReturnsNullTimestamp() { assertThat(converter.to(null)).isNull(); }