public void testWildcardFuture() {
    SettableFuture<String> settable = SettableFuture.create();
    ListenableFuture<?> f = settable;
    FutureCallback<@Nullable Object> callback =
        new FutureCallback<@Nullable Object>() {
          @Override
          public void onSuccess(@Nullable Object result) {}

          @Override
          public void onFailure(Throwable t) {}
        };
    addCallback(f, callback, directExecutor());

 * @since 2.0
 */
@GwtCompatible
public abstract class ForwardingMultiset<E extends @Nullable Object> extends ForwardingCollection<E>
    implements Multiset<E> {

  /** Constructor for use by subclasses. */
  protected ForwardingMultiset() {}

  @Override
  protected abstract Multiset<E> delegate();

  @Override
  public int count(@Nullable Object element) {
    return delegate().count(element);
  }

      final C first = first();

      @Override
      protected @Nullable C computeNext(C previous) {
        return equalsOrThrow(previous, first) ? null : domain.previous(previous);
      }
    };
  }

  private static boolean equalsOrThrow(Comparable<?> left, @Nullable Comparable<?> right) {
    return right != null && Range.compareOrThrow(left, right) == 0;
  }

  @Override

import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import org.jspecify.annotations.Nullable;

/** Methods factored out so that they can be emulated differently in GWT. */
@GwtCompatible
final class Platform {
  static boolean isInstanceOfThrowableClass(
      @Nullable Throwable t, Class<? extends Throwable> expectedClass) {
    return expectedClass.isInstance(t);
  }

 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.cli.transfer;

import java.io.File;

import org.apache.maven.api.annotations.Nullable;
import org.eclipse.aether.transfer.TransferResource;

/**
 * Immutable identifier of a {@link TransferResource}.

 * either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */
package org.codelibs.fess.suggest.index.contents.querylog;

import org.opensearch.common.Nullable;

/**
 * The QueryLog class represents a log entry containing a query string and an optional filter query string.
 */
public class QueryLog {
    private final String q;
    private final String fq;

    /**

     */
    @Nullable
    VersionRange getVersionRange();

    /**
     * Returns the recommended version of this constraint, or {@code null} if none.
     * <p>
     * Note: only one, this method or {@link #getVersionRange()} method must return non-{@code null} value.
     */
    @Nullable
    Version getRecommendedVersion();

    /**

import java.util.List;
import java.util.Map.Entry;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * A container class for the five sample elements we need for testing.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible
@NullMarked
public class SampleElements<E extends @Nullable Object> implements Iterable<E> {
  // TODO: rename e3, e4 => missing1, missing2
  private final E e0;

  @Override
  public E takeLast() throws InterruptedException {
    return delegate().takeLast();
  }

  @Override
  public @Nullable E pollFirst(long timeout, TimeUnit unit) throws InterruptedException {
    return delegate().pollFirst(timeout, unit);
  }

  @Override
  public @Nullable E pollLast(long timeout, TimeUnit unit) throws InterruptedException {
    return delegate().pollLast(timeout, unit);
  }

  @Override

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * Used to test listenable future implementations.
 *
 * @author Sven Mawson
 */
@NullUnmarked
@GwtIncompatible
@J2ktIncompatible
public class ListenableFutureTester {