### Question:
DaysAdjustment implements Resolvable<DateAdjuster>, ImmutableBean, Serializable { public static DaysAdjustment ofBusinessDays(int numberOfDays, HolidayCalendarId holidayCalendar) { if (numberOfDays == 0) { return new DaysAdjustment(0, HolidayCalendarIds.NO_HOLIDAYS, BusinessDayAdjustment.of(FOLLOWING, holidayCalendar)); } return new DaysAdjustment(numberOfDays, holidayCalendar, 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_ofBusinessDays2_null() { assertThatIllegalArgumentException().isThrownBy(() -> DaysAdjustment.ofBusinessDays(2, null)); }
@Test public void test_ofBusinessDays3_null() { assertThatIllegalArgumentException().isThrownBy(() -> DaysAdjustment.ofBusinessDays(3, null, BDA_FOLLOW_SAT_SUN)); assertThatIllegalArgumentException().isThrownBy(() -> DaysAdjustment.ofBusinessDays(3, SAT_SUN, null)); assertThatIllegalArgumentException().isThrownBy(() -> DaysAdjustment.ofBusinessDays(3, null, null)); }