import java.util.Arrays;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.function.ObjIntConsumer;
import javax.annotation.CheckForNull;

/**
 * Multiset implementation specialized for enum elements, supporting all single-element operations
 * in O(1).
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset">{@code Multiset}</a>.

import java.io.Serializable;
import java.util.Arrays;
import java.util.Iterator;
import java.util.NoSuchElementException;
import javax.annotation.CheckForNull;

/**
 * Multiset implementation specialized for enum elements, supporting all single-element operations
 * in O(1).
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset">{@code Multiset}</a>.

  static final RegularImmutableBiMap<Object, Object> EMPTY =
      new RegularImmutableBiMap<Object, Object>();

  // This reference is used both by the GWT compiler to infer the elements
  // of the lists that needs to be serialized.
  private ImmutableBiMap<V, K> inverse;

  @SuppressWarnings("unchecked") // used only for the empty map, which works for any types
  RegularImmutableBiMap() {
    super(new RegularImmutableMap<K, V>(new HashMap<K, V>()));

    `com.google.guava:failureaccess:1.0.2`. It also has
    [some annotation-only dependencies][guava-deps], which we discuss in more
    detail at that link.

4.  Serialized forms of ALL objects are subject to change unless noted
    otherwise. Do not persist these and assume they can be read by a future
    version of the library.

    return new SerializedForm<>(delegate());
  }

  private void readObject(ObjectInputStream stream) throws InvalidObjectException {
    throw new InvalidObjectException("Use SerializedForm");
  }

  /** Serialized form of the map, to avoid serializing the constraint. */
  private static final class SerializedForm<B extends @Nullable Object> implements Serializable {
    private final Map<Class<? extends @NonNull B>, B> backingMap;