import java.util.Map;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * Methods factored out so that they can be emulated differently in GWT.
 *
 * @author Hayward Chan
 */
@GwtCompatible
final class Platform {
  /** Returns the platform preferred implementation of a map based on a hash table. */
  static <K extends @Nullable Object, V extends @Nullable Object>
      Map<K, V> newHashMapWithExpectedSize(int expectedSize) {

          <item index="2" class="java.lang.String" itemvalue="androidx.annotation.RecentlyNullable" />
          <item index="3" class="java.lang.String" itemvalue="com.android.annotations.Nullable" />
          <item index="4" class="java.lang.String" itemvalue="edu.umd.cs.findbugs.annotations.Nullable" />
          <item index="5" class="java.lang.String" itemvalue="io.reactivex.annotations.Nullable" />

    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),
          ToOptionalState::combine,
          state -> {

  // TODO: b/287198172 - Consider eagerly initializing these (but think about serialization).
  @LazyInit private transient @Nullable Ordering<@Nullable Comparable<?>> nullsFirst;
  @LazyInit private transient @Nullable Ordering<@Nullable Comparable<?>> nullsLast;

  @Override
  @SuppressWarnings("unchecked") // TODO(kevinb): the right way to explain this??
  public int compare(Comparable<?> left, Comparable<?> right) {

        }
      }
    };

    abstract <E extends @Nullable Object> void forEach(
        GeneralSpliterator<E> spliterator, Consumer<? super E> consumer);

    static final Set<SpliteratorDecompositionStrategy> ALL_STRATEGIES =
        unmodifiableSet(new LinkedHashSet<>(asList(values())));
  }

  private static <E extends @Nullable Object> @Nullable GeneralSpliterator<E> trySplitTestingSize(

        }
      }
    };

    abstract <E extends @Nullable Object> void forEach(
        GeneralSpliterator<E> spliterator, Consumer<? super E> consumer);

    static final Set<SpliteratorDecompositionStrategy> ALL_STRATEGIES =
        unmodifiableSet(new LinkedHashSet<>(asList(values())));
  }

  private static <E extends @Nullable Object> @Nullable GeneralSpliterator<E> trySplitTestingSize(

  }

  @Override
  public @Nullable E lower(E element) {
    int index = headIndex(element, false) - 1;
    return (index == -1) ? null : elements.get(index);
  }

  @Override
  public @Nullable E floor(E element) {
    int index = headIndex(element, true) - 1;
    return (index == -1) ? null : elements.get(index);
  }

  @Override
  public @Nullable E ceiling(E element) {

    };
  }

  @Override
  public @Nullable Entry<K, V> firstEntry() {
    return delegate.firstEntry();
  }

  @Override
  public K firstKey() {
    return delegate.firstKey();
  }

  @Override
  public @Nullable Entry<K, V> floorEntry(K key) {
    return delegate.floorEntry(checkValid(key));
  }

  @Override
  public @Nullable K floorKey(K key) {

    return (prefix & ~mask) | (suffix & mask);
  }

  static int remove(
      @Nullable Object key,
      @Nullable Object value,
      int mask,
      Object table,
      int[] entries,
      @Nullable Object[] keys,
      @Nullable Object @Nullable [] values) {
    int hash = Hashing.smearedHash(key);
    int tableIndex = hash & mask;
    int next = tableGet(table, tableIndex);

import java.util.concurrent.ConcurrentHashMap;
import org.jspecify.annotations.Nullable;

/**
 * Methods factored out so that they can be emulated differently in GWT.
 *
 * @author Hayward Chan
 */
@GwtCompatible
final class Platform {

  /** Returns the platform preferred implementation of a map based on a hash table. */
  static <K extends @Nullable Object, V extends @Nullable Object>
      Map<K, V> newHashMapWithExpectedSize(int expectedSize) {