### Question:
WhenTaken extends AbstractEntity implements Entity, Comparable<WhenTaken>, TypeWithDuration { public void setOffset(Duration duration) { checkCommited("Offset"); Duration oldValue = d_offset; d_offset = duration; firePropertyChange(PROPERTY_OFFSET, oldValue, d_offset); } WhenTaken(Duration offset, RelativeTo relativeTo, Epoch epoch); Duration getOffset(); void setOffset(Duration duration); RelativeTo getRelativeTo(); void setRelativeTo(RelativeTo relativeTo); Epoch getEpoch(); void setEpoch(Epoch epoch); Duration getDuration(); void setDuration(Duration duration); Set<? extends Entity> getDependencies(); @Override boolean equals(Object obj); @Override String toString(); @Override int compareTo(WhenTaken o); @Override int hashCode(); @Override WhenTaken clone(); void commit(); boolean isCommitted(); static final String PROPERTY_EPOCH; static final String PROPERTY_RELATIVE_TO; static final String PROPERTY_OFFSET; }### Answer:
@Test public void testSetOffset() { Duration duration2 = EntityUtil.createDuration("P28D"); JUnitUtil.testSetter(d_wt, WhenTaken.PROPERTY_OFFSET, d_duration1, duration2); }