*
   * <p>If the graph is directed, {@code edge} will be directed in this graph; otherwise, it will be
   * undirected.
   *
   * <p><b>{@code edge} must be unique to this graph</b>, just as a {@code Map} key must be. It must
   * also be non-null.
   *
   * <p>If {@code nodeU} and {@code nodeV} are not already present in this graph, this method will

   * multiset itself).
   *
   * <p>Despite the method name, this method attempts to avoid actually copying the data when it is
   * safe to do so. The exact circumstances under which a copy will or will not be performed are
   * undocumented and subject to change.
   *
   * <p>This method is not type-safe, as it may be called on elements that are not mutually
   * comparable.
   *

   * generated by applying the specified functions. If multiple inputs are mapped to the same row
   * and column pair, they will be combined with the specified merging function in encounter order.
   *
   * <p>The returned {@code Collector} will throw a {@code NullPointerException} at collection time
   * if the row, column, value, or merging functions return null on any input.
   *
   * @since 21.0
   */

   * future to finish, and when it completes, run the listeners. This implementation will wait on
   * the source future indefinitely, so if the source future never completes, the adapter will never
   * complete either.
   *
   * <p>If the delegate future is interrupted or throws an unexpected unchecked exception, the
   * listeners will not be invoked.
   */

   * map built by MapMaker) no longer has a strong reference to this object, the garbage collector
   * will reclaim it and enqueue the phantom reference. The enqueued reference will trigger the
   * Finalizer to stop.
   *
   * If this library is loaded in the system class loader, FinalizableReferenceQueue can load
   * Finalizer directly with no problems.
   *

   * map built by MapMaker) no longer has a strong reference to this object, the garbage collector
   * will reclaim it and enqueue the phantom reference. The enqueued reference will trigger the
   * Finalizer to stop.
   *
   * If this library is loaded in the system class loader, FinalizableReferenceQueue can load
   * Finalizer directly with no problems.
   *

   * Optional} will be returned from this method and the iterator will be left exhausted: its {@code
   * hasNext()} method will return {@code false}.
   *
   * <p><b>Warning:</b> avoid using a {@code predicate} that matches {@code null}. If {@code null}
   * is matched in {@code iterator}, a NullPointerException will be thrown.
   *
   * @since 11.0
   */

     * not allowed, and will cause {@link #build} to fail.
     */
    @CanIgnoreReturnValue
    @Override
    public Builder<K, V> put(K key, V value) {
      super.put(key, value);
      return this;
    }

    /**
     * Adds the given {@code entry} to the bimap. Duplicate keys or values are not allowed, and will
     * cause {@link #build} to fail.
     *
     * @since 19.0

   * result.
   *
   * @return the next element if there was one. If {@code endOfData} was called during execution,
   *     the return value will be ignored.
   * @throws RuntimeException if any unrecoverable error happens. This exception will propagate
   *     outward to the {@code hasNext()}, {@code next()}, or {@code peek()} invocation that invoked

   * most once unless the underlying {@code get()} throws an exception. The supplier's serialized
   * form does not contain the cached value, which will be recalculated when {@code get()} is called
   * on the deserialized instance.
   *
   * <p>When the underlying delegate throws an exception then this memoizing supplier will keep
   * delegating calls until it returns valid data.