}
    }

    /**
     * Scans the first {@code size} elements of {@code entries} looking for duplicate keys. If
     * duplicates are found, a new correctly-sized array is returned with the same elements (up to
     * {@code size}), except containing only the last occurrence of each duplicate key. Otherwise
     * {@code null} is returned.
     */
    @CheckForNull

   *
   * @throws IllegalArgumentException if duplicate keys or values are added
   */
  public static <K, V> ImmutableBiMap<K, V> of(K k1, V v1, K k2, V v2) {
    return RegularImmutableBiMap.fromEntries(entryOf(k1, v1), entryOf(k2, v2));
  }

  /**
   * Returns an immutable map containing the given entries, in order.
   *
   * @throws IllegalArgumentException if duplicate keys or values are added
   */

    public final E[] elements;
    public final E duplicate;

    private ArrayWithDuplicate(E[] elements, E duplicate) {
      this.elements = elements;
      this.duplicate = duplicate;
    }
  }

  /**
   * @return an array of the proper size with a duplicate element. The size must be at least three.
   */

            .suppressing(SetCreationTester.class.getMethods())
            // BiMap.entrySet() duplicate-handling behavior is too confusing for SetCreationTester
            .withSetUp(parentBuilder.getSetUp())
            .withTearDown(parentBuilder.getTearDown())
            .createTestSuite());
    /*
     * TODO(cpovirk): the Map tests duplicate most of this effort by using a

    @Nullable Object[] alternatingKeysAndValues;
    int size;
    boolean entriesUsed;
    /**
     * If non-null, a duplicate key we found in a previous buildKeepingLast() or buildOrThrow()
     * call. A later buildOrThrow() can simply report this duplicate immediately.
     */
    @Nullable DuplicateKey duplicateKey;

    /**

     * will throw an exception if there are duplicate key pairs. The {@code build()} method will
     * soon be deprecated.
     *
     * @throws IllegalArgumentException if duplicate key pairs were added
     */
    public ImmutableTable<R, C, V> build() {
      return buildOrThrow();
    }

    /**
     * Returns a newly-created immutable table, or throws an exception if duplicate key pairs were
     * added.
     *

        Map<Object, Object> sourceMap = new LinkedHashMap<>();
        for (Entry<?, ?> entry : entries) {
          if (sourceMap.put(entry.getKey(), entry.getValue()) != null) {
            throw new UnsupportedOperationException("duplicate key");
          }
        }
        return ImmutableBiMap.copyOf(sourceMap);
      }
    },
    COPY_OF_ENTRIES {
      @Override
      public ImmutableBiMap<Object, Object> create(List<Entry<?, ?>> entries) {

  /**
   * Indicates that the constructor or factory method of a collection, usually an immutable set,
   * throws an {@link IllegalArgumentException} when presented with duplicate elements instead of
   * collapsing them to a single element or including duplicate instances in the collection.
   */
  REJECTS_DUPLICATES_AT_CREATION,

  SUPPORTS_ADD,
  SUPPORTS_REMOVE,
  SUPPORTS_ITERATOR_REMOVE,

      @CheckForNull
      protected C computeNext() {
        while (merged.hasNext()) {
          C next = merged.next();
          boolean duplicate = lastValue != null && comparator.compare(next, lastValue) == 0;

          // Keep looping till we find a non-duplicate value.
          if (!duplicate) {
            lastValue = next;
            return lastValue;
          }
        }

        }
      }
      elements[n++] = element;
      return this;
    }

    /**
     * Adds each element of {@code elements} to the {@code ImmutableSortedSet}, ignoring duplicate
     * elements (only the first duplicate element is added).
     *
     * @param elements the elements to add
     * @return this {@code Builder} object
     * @throws NullPointerException if {@code elements} contains a null element