func (set TargetIDSet) Union(sset TargetIDSet) TargetIDSet {
	nset := set.Clone()

	for k := range sset {
		nset.add(k)
	}

	return nset
}

// Difference - returns difference with given set as new set.
func (set TargetIDSet) Difference(sset TargetIDSet) TargetIDSet {
	nset := NewTargetIDSet()
	for k := range set {
		if _, ok := sset[k]; !ok {
			nset.add(k)
		}
	}

	return nset
}

  public void testDifference_minSize() {
    assertMinSize(difference(emptySet(), emptySet()), 0);
    assertMinSize(difference(setSize(2), setSize(3)), 0);
    assertMinSize(difference(setSize(3), setSize(2)), 1);
    assertMinSize(difference(setSizeRange(10, 20), setSizeRange(1, 2)), 8);
    assertMinSize(difference(setSizeRange(1, 2), setSizeRange(10, 20)), 0);
    assertMinSize(difference(setSizeRange(10, 20), setSizeRange(11, 12)), 0);

        Instant monotonic = MonotonicClock.now();
        Instant system = Instant.now();

        // The difference should be relatively small (allow for 1 second max)
        Duration difference = Duration.between(monotonic, system).abs();
        assertTrue(difference.getSeconds() <= 1, "Monotonic time should be reasonably aligned with system time");
    }

						</difference>
						<difference>
							<className>jcifs/Configuration</className>
							<differenceType>7012</differenceType>
							<method>java.lang.String getGuestPassword()</method>
						</difference>
						<difference>
							<className>jcifs/SmbResource</className>
							<differenceType>7012</differenceType>
							<method>void setFileTimes(long, long, long)</method>
						</difference>
					</ignored>

func (set TargetIDSet) Union(sset TargetIDSet) TargetIDSet {
	nset := set.Clone()

	for k := range sset {
		nset.add(k)
	}

	return nset
}

// Difference - returns difference with given set as new set.
func (set TargetIDSet) Difference(sset TargetIDSet) TargetIDSet {
	nset := NewTargetIDSet()
	for k := range set {
		if _, ok := sset[k]; !ok {
			nset.add(k)
		}
	}

	return nset
}

## Current Behavior
<!--- If describing a bug, tell us what happens instead of the expected behavior -->
<!--- If suggesting a change/improvement, explain the difference from current behavior -->

## Possible Solution
<!--- Not obligatory, but suggest a fix/reason for the bug, -->
<!--- or ideas how to implement the addition or change -->

## Steps to Reproduce (for bugs)

import org.jspecify.annotations.Nullable;

/**
 * An object representing the differences between two maps.
 *
 * @author Kevin Bourrillion
 * @since 2.0
 */
@DoNotMock("Use Maps.difference")
@GwtCompatible
public interface MapDifference<K extends @Nullable Object, V extends @Nullable Object> {
  /**
   * Returns {@code true} if there are no differences between the two maps; that is, if the maps are
   * equal.
   */

	default:
		return nil, errNotImplemented
	}
	return FromTimestamp(t.Add(duration)), nil
}

// dateDiff computes the difference between two times in terms of the
// `timePart` which can be years, months, days, hours, minutes or
// seconds. For difference in years, months or days, the time part,
// including timezone is ignored.
func dateDiff(timePart string, ts1, ts2 time.Time) (*Value, error) {

    }

    @Test
    void testHeartbeatUpdate() throws InterruptedException {
        long initialTime = registration.getLastHeartbeat();

        Thread.sleep(50); // Ensure sufficient time difference
        registration.updateHeartbeat();

        // After update, should not be expired with long timeout
        assertFalse(registration.isExpired(60000));

        // Verify heartbeat was actually updated

import org.jspecify.annotations.Nullable;

/**
 * An object representing the differences between two maps.
 *
 * @author Kevin Bourrillion
 * @since 2.0
 */
@DoNotMock("Use Maps.difference")
@GwtCompatible
public interface MapDifference<K extends @Nullable Object, V extends @Nullable Object> {
  /**
   * Returns {@code true} if there are no differences between the two maps; that is, if the maps are
   * equal.
   */