protected EmptyIteratorTester() {
      super(3, MODIFIABLE, Collections.<Integer>emptySet(), IteratorTester.KnownOrder.KNOWN_ORDER);
    }
  }

  @GwtIncompatible // Only used by @GwtIncompatible code
  private abstract static class SingletonIteratorTester extends IteratorTester<Integer> {
    protected SingletonIteratorTester() {
      super(3, MODIFIABLE, singleton(1), IteratorTester.KnownOrder.KNOWN_ORDER);
    }
  }

    protected EmptyIteratorTester() {
      super(3, MODIFIABLE, Collections.<Integer>emptySet(), IteratorTester.KnownOrder.KNOWN_ORDER);
    }
  }

  @GwtIncompatible // Only used by @GwtIncompatible code
  private abstract static class SingletonIteratorTester extends IteratorTester<Integer> {
    protected SingletonIteratorTester() {
      super(3, MODIFIABLE, singleton(1), IteratorTester.KnownOrder.KNOWN_ORDER);
    }
  }

     */
    fun connectionPool(connectionPool: ConnectionPool) =
      apply {
        this.connectionPool = connectionPool
      }

    /**
     * Returns a modifiable list of interceptors that observe the full span of each call: from
     * before the connection is established (if any) until after the response source is selected
     * (either the origin server, cache, or both).
     */

    }

    /**
     * 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

            setActiveProfiles((Collections.unmodifiableList(project.getActiveProfiles())));
        }

        if (project.getAttachedArtifacts() != null) {
            // clone properties modifiable by plugins in a forked lifecycle
            setAttachedArtifacts(new ArrayList<>(project.getAttachedArtifacts()));
        }

        if (project.getCompileSourceRoots() != null) {

  }

  /**
   * Returns an unmodifiable view of the specified collection, preserving the interface for
   * instances of {@code SortedSet}, {@code Set}, {@code List} and {@code Collection}, in that order
   * of preference.
   *
   * @param collection the collection for which to return an unmodifiable view
   * @return an unmodifiable view of the collection
   */

import static com.google.common.collect.Sets.powerSet;
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;

  }

  /** Returns an unmodifiable view of {@code iterator}. */
  public static <T extends @Nullable Object> UnmodifiableIterator<T> unmodifiableIterator(
      Iterator<? extends T> iterator) {
    checkNotNull(iterator);
    if (iterator instanceof UnmodifiableIterator) {
      @SuppressWarnings("unchecked") // Since it's unmodifiable, the covariant cast is safe

  }

  /** Returns an unmodifiable view of {@code iterator}. */
  public static <T extends @Nullable Object> UnmodifiableIterator<T> unmodifiableIterator(
      Iterator<? extends T> iterator) {
    checkNotNull(iterator);
    if (iterator instanceof UnmodifiableIterator) {
      @SuppressWarnings("unchecked") // Since it's unmodifiable, the covariant cast is safe

    /* No aliasing on inverse operations. */
    assertSame(unmod.inverse(), unmod.inverse());
    assertSame(unmod, unmod.inverse().inverse());

    /* Unmodifiable is a view. */
    mod.put(4, "four");
    assertEquals(true, unmod.get(4).equals("four"));
    assertEquals(true, unmod.inverse().get("four").equals(4));