*
   * <p><b>{@code Stream} equivalent:</b> {@code stream.filter(predicate).findFirst()}.
   */
  public final Optional<@NonNull E> firstMatch(Predicate<? super E> predicate) {
    // Unsafe, but we can't do much about it now.
    return Iterables.<@NonNull E>tryFind((Iterable<@NonNull E>) getDelegate(), predicate);
  }

  /**
   * Returns a fluent iterable that applies {@code function} to each element of this fluent

   *
   * <p><b>{@code Stream} equivalent:</b> {@code stream.filter(predicate).findFirst()}.
   */
  public final Optional<@NonNull E> firstMatch(Predicate<? super E> predicate) {
    // Unsafe, but we can't do much about it now.
    return Iterables.<@NonNull E>tryFind((Iterable<@NonNull E>) getDelegate(), predicate);
  }

  /**
   * Returns a fluent iterable that applies {@code function} to each element of this fluent

      Class<? super @NonNull E> type, E... contents) {
    return new MinimalCollection<>(type, true, contents);
  }

  private final E[] contents;
  private final Class<? super @NonNull E> type;
  private final boolean allowNulls;

  // Package-private so that it can be extended.
  MinimalCollection(Class<? super @NonNull E> type, boolean allowNulls, E... contents) {

        new ListFuture<V>(ImmutableList.copyOf(futures), true);
    // allAsList ensures that it fills the output list with V instances.
    @SuppressWarnings("nullness")
    ListenableFuture<List<V>> nonNull = nullable;
    return nonNull;
  }

  /**
   * Creates a new {@code ListenableFuture} whose value is a list containing the values of all its
   * input futures, if all succeed.
   *

      throw new UnsupportedOperationException();
    }

    @Override
    public @Nullable V merge(
        K key,
        @NonNull V value,
        BiFunction<? super @NonNull V, ? super @NonNull V, ? extends @Nullable V> function) {
      throw new UnsupportedOperationException();
    }

    @Override
    public BiMap<V, K> inverse() {

      assertEquals(strictlyOrderedList, ordering.sortedCopy(shuffledList));

      if (!strictlyOrderedList.contains(null)) {
        List<@NonNull T> nonNullShuffledList = (List<@NonNull T>) shuffledList;
        assertEquals(strictlyOrderedList, ordering.immutableSortedCopy(nonNullShuffledList));
      }
    }
  }

  /**

      assertEquals(strictlyOrderedList, ordering.sortedCopy(shuffledList));

      if (!strictlyOrderedList.contains(null)) {
        List<@NonNull T> nonNullShuffledList = (List<@NonNull T>) shuffledList;
        assertEquals(strictlyOrderedList, ordering.immutableSortedCopy(nonNullShuffledList));
      }
    }
  }

  /**

        strategy.forEach(spliteratorSupplier.get(), resultsForStrategy::add);

        // TODO(cpovirk): better failure messages
        if ((characteristics & Spliterator.NONNULL) != 0) {
          assertFalse(resultsForStrategy.contains(null));
        }
        if ((characteristics & Spliterator.SORTED) != 0) {
          Comparator<? super E> comparator = spliterator.getComparator();

        strategy.forEach(spliteratorSupplier.get(), resultsForStrategy::add);

        // TODO(cpovirk): better failure messages
        if ((characteristics & Spliterator.NONNULL) != 0) {
          assertFalse(resultsForStrategy.contains(null));
        }
        if ((characteristics & Spliterator.SORTED) != 0) {
          Comparator<? super E> comparator = spliterator.getComparator();

import java.util.TreeMap;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.function.BinaryOperator;
import java.util.stream.Collector;
import org.jspecify.annotations.NonNull;
import org.jspecify.annotations.Nullable;

/**
 * Static utility methods pertaining to {@link Map} instances (including instances of {@link