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

    @GwtIncompatible // Spliterator
    Spliterator<Cell<C, R, V>> cellSpliterator() {
      return CollectSpliterators.map(
          original.cellSet().spliterator(),
          Spliterator.DISTINCT | Spliterator.NONNULL,
          Tables::transposeCell);
    }
  }

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

                0,
                (Entry<C, V> columnEntry) ->
                    immutableCell(rowEntry.getKey(), columnEntry.getKey(), columnEntry.getValue())),
        Spliterator.DISTINCT | Spliterator.SIZED | Spliterator.NONNULL,
        size());
  }

  @Override
  public Map<C, V> row(R rowKey) {
    return new Row(rowKey);
  }

  class Row extends IteratorBasedAbstractMap<C, V> {
    final R rowKey;

    @Override
    @GwtIncompatible // Spliterator
    Spliterator<Entry<K, V>> entrySpliterator() {
      return CollectSpliterators.indexed(
          size(), Spliterator.ORDERED | Spliterator.DISTINCT | Spliterator.NONNULL, this::getEntry);
    }

    // TODO(lowasser): consider an optimized values() implementation

    @Override
    public boolean containsKey(@Nullable Object key) {
      return keyIndex.containsKey(key);

      }

      @Override
      public int characteristics() {
        return fromSpliterator.characteristics()
            & (Spliterator.DISTINCT
                | Spliterator.NONNULL
                | Spliterator.ORDERED
                | Spliterator.SORTED);
      }
    }
    return new Splitr();
  }

  /**

          Collection<V> valueCollection = keyToValueCollectionEntry.getValue();
          return CollectSpliterators.map(
              valueCollection.spliterator(),
              Spliterator.DISTINCT | Spliterator.NONNULL,
              (V value) -> immutableEntry(key, value));
        },
        Spliterator.SIZED,
        size());
  }

  @Override
  public void forEach(BiConsumer<? super K, ? super V> action) {

      }
    };
  }

  @Override
  Spliterator<Entry<K, V>> entrySpliterator() {
    return Spliterators.spliterator(
        entries(), Spliterator.DISTINCT | Spliterator.ORDERED | Spliterator.NONNULL);
  }

  @Override
  Iterator<V> valueIterator() {
    return Maps.valueIterator(entryIterator());
  }

  @Override
  Spliterator<V> valueSpliterator() {

   * the spliterator implementation.
   */
  static final int SPLITERATOR_CHARACTERISTICS =
      Spliterator.IMMUTABLE | Spliterator.NONNULL | Spliterator.ORDERED;

  ImmutableCollection() {}

  /** Returns an unmodifiable iterator across the elements in this collection. */
  @Override
  public abstract UnmodifiableIterator<E> iterator();

                .getOrDefault(artifact.getArtifactId(), Collections.emptyMap())
                .values()
                .stream()
                .filter(p -> Objects.nonNull(findArtifact(p, artifact, false)))
                .map(MavenProject::getVersion)
                .collect(Collectors.collectingAndThen(Collectors.toList(), Collections::unmodifiableList));
    }

    @Override

  // (which is fortunate because Animal Sniffer doesn't look for @IgnoreJRERequirement on fields)
  static final int SPLITERATOR_CHARACTERISTICS =
      Spliterator.IMMUTABLE | Spliterator.NONNULL | Spliterator.ORDERED;

  ImmutableCollection() {}

  /** Returns an unmodifiable iterator across the elements in this collection. */
  @Override
  public abstract UnmodifiableIterator<E> iterator();