### Question:
DaysAdjustment implements Resolvable<DateAdjuster>, ImmutableBean, Serializable { public static DaysAdjustment ofCalendarDays(int numberOfDays) { return new DaysAdjustment(numberOfDays, HolidayCalendarIds.NO_HOLIDAYS, BusinessDayAdjustment.NONE); } private  DaysAdjustment(
      int days,
      HolidayCalendarId calendar,
      BusinessDayAdjustment adjustment); static DaysAdjustment ofCalendarDays(int numberOfDays); static DaysAdjustment ofCalendarDays(int numberOfDays, BusinessDayAdjustment adjustment); static DaysAdjustment ofBusinessDays(int numberOfDays, HolidayCalendarId holidayCalendar); static DaysAdjustment ofBusinessDays(
      int numberOfDays,
      HolidayCalendarId holidayCalendar,
      BusinessDayAdjustment adjustment); LocalDate adjust(LocalDate date, ReferenceData refData); @Override DateAdjuster resolve(ReferenceData refData); HolidayCalendarId getResultCalendar(); DaysAdjustment normalized(); @Override String toString(); static DaysAdjustment.Meta meta(); static DaysAdjustment.Builder builder(); @Override DaysAdjustment.Meta metaBean(); int getDays(); HolidayCalendarId getCalendar(); BusinessDayAdjustment getAdjustment(); Builder toBuilder(); @Override boolean equals(Object obj); @Override int hashCode(); static final DaysAdjustment NONE; }### Answer:
@Test public void test_ofCalendarDays2_null() { assertThatIllegalArgumentException().isThrownBy(() -> DaysAdjustment.ofCalendarDays(2, null)); }
@Test public void coverage() { coverImmutableBean(DaysAdjustment.ofCalendarDays(4, BDA_FOLLOW_SAT_SUN)); }
@Test public void test_serialization() { assertSerialization(DaysAdjustment.ofCalendarDays(4, BDA_FOLLOW_SAT_SUN)); }