import static com.google.common.collect.Lists.transform;
import static com.google.common.collect.ReflectionFreeAssertThrows.assertThrows;
import static com.google.common.collect.testing.IteratorFeature.UNMODIFIABLE;
import static com.google.common.truth.Truth.assertThat;
import static java.lang.System.arraycopy;
import static java.util.Arrays.asList;
import static java.util.Collections.emptyList;

    }

    /**
     * Scope the return type to {@link UnmodifiableIterator} to ensure this is an unmodifiable view.
     *
     * @since 20.0 (present with return type {@link Iterator} since 2.0)
     */
    @Override
    public abstract UnmodifiableIterator<E> iterator();
  }

  /**
   * Returns an unmodifiable <b>view</b> of the union of two sets. The returned set contains all

   * could throw during the invocation of that method. This is necessary because, e.g., a call to
   * {@code iterator().remove()} of an unmodifiable list could throw either {@link
   * IllegalStateException} or {@link UnsupportedOperationException}. Note that iterator
   * implementations should always throw one of the exceptions in a {@code PermittedExceptions}

    @Nullable Object[] result = new @Nullable Object[contents.length];
    arraycopy(contents, 0, result, 0, contents.length);
    return result;
  }

  /*
   * a "type A" unmodifiable collection freaks out proactively, even if there
   * wasn't going to be any actual work to do anyway
   */

  @Override
  public boolean addAll(Collection<? extends E> elementsToAdd) {
    throw up();
  }

    new IteratorTester<String>(
        5, UNMODIFIABLE, singleton("a"), IteratorTester.KnownOrder.KNOWN_ORDER) {
      @Override
      protected Iterator<String> newTargetIterator() {
        return of("a").iterator();
      }
    }.test();
  }

  @GwtIncompatible // slow (~30s)
  public void testIterator_general() {
    new IteratorTester<String>(

import static com.google.common.collect.Sets.toImmutableEnumSet;
import static com.google.common.collect.Sets.unmodifiableNavigableSet;
import static com.google.common.collect.testing.IteratorFeature.UNMODIFIABLE;
import static com.google.common.truth.Truth.assertThat;
import static com.google.common.truth.Truth.assertWithMessage;
import static java.io.ObjectStreamConstants.TC_REFERENCE;

 * AbstractGraphBuilder}.
 *
 * <p>This class maintains a map of nodes to {@link GraphConnections}.
 *
 * <p>Collection-returning accessors return unmodifiable views: the view returned will reflect
 * changes to the graph (if the graph is mutable) but may not be modified by the user.
 *
 * <p>The time complexity of all collection-returning accessors is O(1), since views are returned.

 *       order)
 * </ul>
 *
 * <p>{@code ValueGraph}s built by this class also guarantee that each collection-returning accessor
 * returns a <b>(live) unmodifiable view</b>; see <a
 * href="https://github.com/google/guava/wiki/GraphsExplained#accessor-behavior">the external
 * documentation</a> for details.
 *
 * <p>Examples of use:
 *
 * <pre>{@code

      @SuppressWarnings("rawtypes") // JDT-based J2KT Java frontend does not permit the direct cast
      Map rawMap = map;
      @SuppressWarnings("unchecked") // covariant casts safe (unmodifiable)
      ImmutableClassToInstanceMap<B> cast = (ImmutableClassToInstanceMap<B>) rawMap;
      return cast;
    }
    return new Builder<B>().putAll(map).build();
  }

   * could throw during the invocation of that method. This is necessary because, e.g., a call to
   * {@code iterator().remove()} of an unmodifiable list could throw either {@link
   * IllegalStateException} or {@link UnsupportedOperationException}. Note that iterator
   * implementations should always throw one of the exceptions in a {@code PermittedExceptions}