assertThrows(IllegalArgumentException.class, () -> Doubles.ensureCapacity(ARRAY1, 1, -1));
  }

  @GwtIncompatible // Double.toString returns different value in GWT.
  public void testJoin() {
    assertThat(Doubles.join(",", EMPTY)).isEmpty();
    assertThat(Doubles.join(",", ARRAY1)).isEqualTo("1.0");
    assertThat(Doubles.join(",", 1.0, 2.0)).isEqualTo("1.0,2.0");

    // It would be nice to be able to return a real concurrent
    // collection like ConcurrentLinkedQueue, so that e.g. concurrent
    // iteration would work, but that would not be GWT-compatible.
    // We are not "just" inheriting from ArrayList here as this doesn't work for J2kt.
    return new AbstractList<T>() {
      final ArrayList<T> data = new ArrayList<>();

      @Override

import org.jspecify.annotations.NullUnmarked;

/**
 * Run collection tests on wrappers from {@link Multimaps}.
 *
 * @author Jared Levy
 */
@GwtIncompatible // suite // TODO(cpovirk): set up collect/gwt/suites version
@NullUnmarked
@AndroidIncompatible // test-suite builders
public class MultimapsCollectionTest extends TestCase {

  private static final Feature<?>[] FOR_MAP_FEATURES_ONE = {
    CollectionSize.ONE,

              stats[2]++;
              break;
            case SIZE:
              stats[3]++;
              break;
            default:
              throw new IllegalStateException("No collected exceptions in GWT CacheBuilder.");
          }
        };

    Cache<Integer, Integer> cache =
        CacheBuilder.newBuilder()
            .expireAfterWrite(1000, MILLISECONDS)
            .removalListener(countingListener)

   * @throws NullPointerException if {@code elements} contains a null element
   */
  public static <E> ImmutableList<E> copyOf(Iterable<? extends E> elements) {
    checkNotNull(elements); // TODO(kevinb): is this here only for GWT?
    return (elements instanceof Collection)
        ? copyOf((Collection<? extends E>) elements)
        : copyOf(elements.iterator());
  }

  /**

   * instance, since {@code PermittedExceptions} is thrown only when a method call is invalid.
   *
   * <p>This class is accessible but not supported in GWT as it references {@link
   * PermittedMetaException}.
   */
  protected final class MultiExceptionListIterator implements ListIterator<E> {
    // TODO: track seen elements when order isn't guaranteed

   *     greater than {@code b}; or zero if they are equal
   */
  @SuppressWarnings("InlineMeInliner") // Integer.compare unavailable under GWT+J2CL
  public static int compare(long a, long b) {
    return Longs.compare(flip(a), flip(b));
  }

  /**
   * Returns the least value present in {@code array}, treating values as unsigned.
   *

              stats[2]++;
              break;
            case SIZE:
              stats[3]++;
              break;
            default:
              throw new IllegalStateException("No collected exceptions in GWT CacheBuilder.");
          }
        };

    Cache<Integer, Integer> cache =
        CacheBuilder.newBuilder()
            .expireAfterWrite(1000, MILLISECONDS)
            .removalListener(countingListener)

   *     greater than {@code b}; or zero if they are equal
   */
  @SuppressWarnings("InlineMeInliner") // Integer.compare unavailable under GWT+J2CL
  public static int compare(int a, int b) {
    return Ints.compare(flip(a), flip(b));
  }

  /**
   * Returns the value of the given {@code int} as a {@code long}, when treated as unsigned.
   *

 * to prioritize memory over CPU.
 *
 * @author Dimitris Andreou
 * @author Jon Noack
 */
@GwtIncompatible // not worth using in GWT for now
class CompactHashSet<E extends @Nullable Object> extends AbstractSet<E> implements Serializable {
  // TODO(user): cache all field accesses in local vars

  /** Creates an empty {@code CompactHashSet} instance. */