public static <T> Collector<T, ?, Optional<T>> toOptional() {
    return (Collector) TO_OPTIONAL;
  }

  private static final Object NULL_PLACEHOLDER = new Object();

  private static final Collector<@Nullable Object, ?, @Nullable Object> ONLY_ELEMENT =
      Collector.<@Nullable Object, ToOptionalState, @Nullable Object>of(
          ToOptionalState::new,
          (state, o) -> state.add((o == null) ? NULL_PLACEHOLDER : o),

	if crypto.S3.IsRequested(r.Header) || crypto.S3KMS.IsRequested(r.Header) { // If SSE-S3 or SSE-KMS present -> AWS fails with undefined error
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrBadRequest), r.URL)
		return
	}

	zipPath, object, err := splitZipExtensionPath(object)
	if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)

   */
  public static <R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
      Table<R, C, V> unmodifiableTable(Table<? extends R, ? extends C, ? extends V> table) {
    return new UnmodifiableTable<>(table);
  }

  private static class UnmodifiableTable<
          R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>

        public void setVersionNo(Long versionNo) {
            this.versionNo = versionNo;
        }

        @Override
        public Map<String, Object> toSource() {
            return sourceMap;
        }

        public void setSourceMap(Map<String, Object> sourceMap) {
            this.sourceMap = sourceMap;
        }

        @Override
        public String getEventType() {
            return eventType;

/**
 * Abstract implementation of {@link InvocationHandler} that handles {@link Object#equals}, {@link
 * Object#hashCode} and {@link Object#toString}. For example:
 *
 * <pre>
 * class Unsupported extends AbstractInvocationHandler {
 *   protected Object handleInvocation(Object proxy, Method method, Object[] args) {
 *     throw new UnsupportedOperationException();
 *   }
 * }
 *

import com.google.common.collect.testing.features.MapFeature;
import java.util.List;
import java.util.Map.Entry;
import org.junit.Ignore;

/**
 * Testers for {@link ListMultimap#put(Object, Object)}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")

  @SuppressWarnings("FutureReturnValueIgnored")
  @Footprint(exclude = {Runnable.class, Executor.class, Thread.class, Exception.class})
  public Object measureSize() {
    for (Thread thread : blockedThreads) {
      thread.interrupt();
    }
    blockedThreads.clear();
    Facade<Object> f = impl.newFacade();
    for (int i = 0; i < numThreads; i++) {
      Thread thread =
          new Thread() {
            @Override

// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@NullMarked
public abstract class AbstractCollectionTester<E extends @Nullable Object>
    extends AbstractContainerTester<Collection<E>, E> {

  // TODO: replace this with an accessor.
  protected Collection<E> collection;

  @Override
  protected Collection<E> actualContents() {

 *   }
 * </pre>
 *
 * @author Kevin Bourrillion
 * @since 10.0
 */
@GwtCompatible
@NullMarked
public class TestLogHandler extends Handler {
  private final Object lock = new Object();

  /** We will keep a private list of all logged records */
  @GuardedBy("lock")
  private final List<LogRecord> list = new ArrayList<>();

  /** Adds the most recently logged record to our list. */

// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@NullMarked
public abstract class AbstractCollectionTester<E extends @Nullable Object>
    extends AbstractContainerTester<Collection<E>, E> {

  // TODO: replace this with an accessor.
  protected Collection<E> collection;

  @Override
  protected Collection<E> actualContents() {