assertTrue(multimap().keySet().contains(entry.getKey()));
    }
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(ALLOWS_NULL_KEYS)
  public void testKeySetContainsNullKeyPresent() {
    initMultimapWithNullKey();
    assertTrue(multimap().keySet().contains(null));
  }

  @MapFeature.Require(ALLOWS_NULL_KEY_QUERIES)
  public void testKeySetContainsNullKeyAbsent() {

For most migration scenarios, we recommend using the modern JSON Search API (`/api/v1/documents`) instead.

### Admin APIs

All admin APIs require authentication (`-u admin:admin` or Bearer token).

**Base Path**: `/api/admin/`

**Available Endpoints**:
- `POST /backup/upload` - Upload backup/import files
- `GET /backup/export` - Export configurations

  @CollectionFeature.Require(SUPPORTS_ADD)
  @CollectionSize.Require(absent = ZERO)
  public void testAdd_supportedPresent() {
    assertTrue("add(present) should return true", getList().add(e0()));
    expectAdded(e0());
  }

  @CollectionFeature.Require(absent = SUPPORTS_ADD)
  @CollectionSize.Require(absent = ZERO)
  /*
   * absent = ZERO isn't required, since unmodList.add() must

  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testRemoveAllPropagatesToGet() {
    Collection<V> getResult = multimap().get(k0());

    multimap().removeAll(k0());

    assertEmpty(getResult);
    expectMissing(e0());
  }

  @CollectionSize.Require(SEVERAL)
  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testRemoveAllMultipleValues() {

public class MapForEachTester<K, V> extends AbstractMapTester<K, V> {
  @CollectionFeature.Require(KNOWN_ORDER)
  public void testForEachKnownOrder() {
    List<Entry<K, V>> entries = new ArrayList<>();
    getMap().forEach((k, v) -> entries.add(entry(k, v)));
    assertEquals(getOrderedElements(), entries);
  }

  @CollectionFeature.Require(absent = KNOWN_ORDER)
  public void testForEachUnknownOrder() {

  @CollectionFeature.Require(SUPPORTS_ADD)
  @CollectionSize.Require(absent = ZERO)
  public void testAdd_supportedPresent() {
    assertTrue("add(present) should return true", getList().add(e0()));
    expectAdded(e0());
  }

  @CollectionFeature.Require(absent = SUPPORTS_ADD)
  @CollectionSize.Require(absent = ZERO)
  /*
   * absent = ZERO isn't required, since unmodList.add() must

@SuppressWarnings("JUnit4ClassUsedInJUnit3")
public class QueueElementTester<E> extends AbstractQueueTester<E> {
  @CollectionSize.Require(ZERO)
  public void testElement_empty() {
    assertThrows(NoSuchElementException.class, () -> getQueue().element());
    expectUnchanged();
  }

  @CollectionSize.Require(ONE)
  public void testElement_size1() {
    assertEquals("size1Queue.element() should return first element", e0(), getQueue().element());

    extends AbstractMultimapTester<K, V, Multimap<K, V>> {
  @CollectionSize.Require(absent = ZERO)
  public void testContainsValueYes() {
    assertTrue(multimap().containsValue(v0()));
  }

  public void testContainsValueNo() {
    assertFalse(multimap().containsValue(v3()));
  }

  @MapFeature.Require(ALLOWS_NULL_VALUES)
  @CollectionSize.Require(absent = ZERO)
  public void testContainsNullValueYes() {

public class MapForEachTester<K, V> extends AbstractMapTester<K, V> {
  @CollectionFeature.Require(KNOWN_ORDER)
  public void testForEachKnownOrder() {
    List<Entry<K, V>> entries = new ArrayList<>();
    getMap().forEach((k, v) -> entries.add(entry(k, v)));
    assertEquals(getOrderedElements(), entries);
  }

  @CollectionFeature.Require(absent = KNOWN_ORDER)
  public void testForEachUnknownOrder() {

    extends AbstractMultimapTester<K, V, Multimap<K, V>> {

  @MapFeature.Require({SUPPORTS_PUT, SUPPORTS_REMOVE, ALLOWS_NULL_VALUES})
  public void testReplaceValuesWithNullValue() {
    List<V> values = asList(v0(), null, v3());
    multimap().replaceValues(k0(), values);
    assertGet(k0(), values);
  }

  @MapFeature.Require({SUPPORTS_PUT, SUPPORTS_REMOVE, ALLOWS_NULL_KEYS})
  public void testReplaceValuesWithNullKey() {