@Override
  public Comparator<? super E> comparator() {
    return comparator;
  }

  @Override
  public @Nullable Entry<E> firstEntry() {
    Iterator<Entry<E>> entryIterator = entryIterator();
    return entryIterator.hasNext() ? entryIterator.next() : null;
  }

  @Override
  public @Nullable Entry<E> lastEntry() {
    Iterator<Entry<E>> entryIterator = descendingEntryIterator();

  abstract <R> @Nullable R dummyReturnValue(TypeToken<R> returnType);

  private final class DummyHandler extends AbstractInvocationHandler implements Serializable {
    private final TypeToken<?> interfaceType;

    DummyHandler(TypeToken<?> interfaceType) {
      this.interfaceType = interfaceType;
    }

    @Override
    protected @Nullable Object handleInvocation(

  public abstract UnmodifiableIterator<E> iterator();

  @Override
  public boolean contains(@Nullable Object object) {
    return object != null && super.contains(object);
  }

  @Override
  public final boolean add(E e) {
    throw new UnsupportedOperationException();
  }

  @Override
  public final boolean remove(@Nullable Object object) {
    throw new UnsupportedOperationException();
  }

  @Override

   * equal to any other equality groups added to this tester.
   *
   * <p>The {@code @Nullable} annotations on the {@code equalityGroup} parameter imply that the
   * objects, and the array itself, can be null. That is for programmer convenience, when the
   * objects come from factory methods that are themselves {@code @Nullable}. In reality neither the
   * array nor its contents can be null, but it is not useful to force the use of {@code

import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/** Replacements for JUnit's {@code assertThrows} that work under GWT/J2CL. */
@GwtCompatible
@NullMarked
final class ReflectionFreeAssertThrows {
  interface ThrowingRunnable {
    void run() throws Throwable;
  }

  interface ThrowingSupplier {
    @Nullable Object get() throws Throwable;
  }

  @CanIgnoreReturnValue

		case "bonus":
			// allow to change non-nullable to nullable
			if nullable, _ := columnType.Nullable(); !nullable {
				t.Fatalf("bonus's nullable should be true, bug got %t", nullable)
			}
		case "stock":
			// do not allow to change nullable to non-nullable
			if nullable, _ := columnType.Nullable(); !nullable {
				t.Fatalf("stock's nullable should be true, bug got %t", nullable)
			}
		}
	}
}

import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import java.util.stream.Collector;
import jsinterop.annotations.JsMethod;
import org.jspecify.annotations.Nullable;

/**
 * GWT emulated version of {@link com.google.common.collect.ImmutableSet}. For the unsorted sets,
 * they are thin wrapper around {@link java.util.Collections#emptySet()}, {@link

    runConcurrentTest(
        numberOfThreads,
        new Callable<@Nullable Void>() {
          @Override
          public @Nullable Void call() throws Exception {
            long unused = ticker.read();
            return null;
          }
        });

    assertEquals(incrementByNanos * numberOfThreads, ticker.read());
  }

  /** Runs {@code callable} concurrently {@code numberOfThreads} times. */

    TreeMultimap<@Nullable String, @Nullable Integer> multimap = createPopulate();
    assertThat(multimap.entries())
        .containsExactly(
            Maps.<@Nullable String, Integer>immutableEntry(null, 7),
            Maps.<@Nullable String, Integer>immutableEntry(null, 3),
            Maps.<@Nullable String, Integer>immutableEntry(null, 1),
            Maps.<String, @Nullable Integer>immutableEntry("tree", null),

     */
    @FunctionalInterface
    public interface ClosingFunction5<
        V1 extends @Nullable Object,
        V2 extends @Nullable Object,
        V3 extends @Nullable Object,
        V4 extends @Nullable Object,
        V5 extends @Nullable Object,
        U extends @Nullable Object> {
      /**
       * Applies this function to five inputs, or throws an exception if unable to do so.
       *