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());
    expectUnchanged();
  }

  @CollectionFeature.Require(KNOWN_ORDER)
  @CollectionSize.Require(SEVERAL)

  }

  @Override
  public boolean contains(@Nullable Object element) {
    return count(element) > 0;
  }

  // Modification Operations
  @CanIgnoreReturnValue
  @Override
  public final boolean add(@ParametricNullness E element) {
    add(element, 1);
    return true;
  }

  @CanIgnoreReturnValue
  @Override
  public int add(@ParametricNullness E element, int occurrences) {
    throw new UnsupportedOperationException();

/**
 * Implementation of {@link ImmutableList} with exactly one element.
 *
 * @author Hayward Chan
 */
@GwtCompatible
@SuppressWarnings("serial") // uses writeReplace(), not default serialization
final class SingletonImmutableList<E> extends ImmutableList<E> {

  final transient E element;

  SingletonImmutableList(E element) {
    this.element = checkNotNull(element);
  }

  @Override
  public E get(int index) {

        }

        Document document = parent.getOwnerDocument();

        Element section = document.createElement("section");
        parent.appendChild(section);

        Element title = document.createElement("title");
        section.appendChild(title);
        title.appendChild(document.createTextNode("Methods added by the "));
        Element literal = document.createElement("literal");
        title.appendChild(literal);

    return rowKeyToIndex.containsKey(rowKey);
  }

  @Override
  public boolean containsValue(@Nullable Object value) {
    for (@Nullable V[] row : array) {
      for (V element : row) {
        if (Objects.equals(value, element)) {
          return true;
        }
      }
    }
    return false;
  }

  @Override
  public @Nullable V get(@Nullable Object rowKey, @Nullable Object columnKey) {

  public void testBuilderAddArrayHandlesNulls() {
    @Nullable String[] elements = new @Nullable String[] {"a", null, "b"};
    ImmutableList.Builder<String> builder = ImmutableList.builder();
    assertThrows(NullPointerException.class, () -> builder.add((String[]) elements));
    ImmutableList<String> result = builder.build();

    /*
     * Maybe it rejects all elements, or maybe it adds "a" before failing.
     * Either way is fine with us.

Args = -H:+AddAllCharsets --enable-http --enable-https --features=okhttp3.internal.graal.OkHttpFeature --report-unsupported-elements-at-runtime...

   */
  @Override
  <T extends @Nullable Object> ListenableFuture<T> submit(
      Runnable task, @ParametricNullness T result);

  /**
   * {@inheritDoc}
   *
   * <p>All elements in the returned list must be {@link ListenableFuture} instances. The easiest
   * way to obtain a {@code List<ListenableFuture<T>>} from this method is an unchecked (but safe)
   * cast:
   *
   * <pre>

  <!--
   | With toolchains you can refer to installations on your system. This
   | way you don't have to hardcode paths in your pom.xml.
   |
   | Every toolchain consist of 3 elements:
   | * type: the type of tool. An often used value is 'jdk'. Toolchains-aware
   |   plugins should document which type you must use.
   |
   | * provides: A list of key/value-pairs.

import org.apache.maven.project.ExtensionDescriptorBuilder;
import org.codehaus.plexus.classworlds.realm.ClassRealm;

/**
 * Provides information about artifacts (identified by groupId:artifactId string key) and classpath elements exported by
 * Maven core itself or a Maven core extension.
 *
 * @since 3.3.0
 */
public class CoreExtensionEntry {
    private final ClassRealm realm;

    private final Set<String> artifacts;