assertEquals(mutable, copy);
      }

      ImmutableRangeSet<Integer> built = builder.build();
      assertEquals(mutable, built);
      assertEquals(ImmutableRangeSet.copyOf(mutable), built);
      assertEquals(mutable.complement(), built.complement());

      for (int i = 0; i <= 11; i++) {
        assertEquals(mutable.contains(i), built.contains(i));
      }

    @Test
    @DisplayName("ltime field is mutable")
    void testLtimeField() {
        TestLocking t = new TestLocking();

        // Initial value
        assertEquals(0L, t.ltime, "ltime should start at 0");

        // Set new value
        long currentTime = System.currentTimeMillis();
        t.ltime = currentTime;
        assertEquals(currentTime, t.ltime, "ltime should be mutable");
    }

    @Test

 *
 * <h3>Implementations</h3>
 *
 * <ul>
 *   <li>{@link ImmutableListMultimap}
 *   <li>{@link ImmutableSetMultimap}
 *   <li>Configure your own mutable multimap with {@link MultimapBuilder}
 *   <li>{@link LinkedListMultimap} (for one unusual kind of mutable {@code Multimap})
 * </ul>
 *
 * Guava contains a number of other multimap implementations, such as {@link ArrayListMultimap}. In

 * @author Mike Bostock
 * @author Louis Wasserman
 * @since 2.0
 */
@GwtCompatible
public final class Lists {
  private Lists() {}

  // ArrayList

  /**
   * Creates a <i>mutable</i>, empty {@code ArrayList} instance.
   *
   * <p><b>Note:</b> if mutability is not required, use {@link ImmutableList#of()} instead.
   *

 * @author Mike Bostock
 * @author Louis Wasserman
 * @since 2.0
 */
@GwtCompatible
public final class Lists {
  private Lists() {}

  // ArrayList

  /**
   * Creates a <i>mutable</i>, empty {@code ArrayList} instance.
   *
   * <p><b>Note:</b> if mutability is not required, use {@link ImmutableList#of()} instead.
   *

 *
 * <h3>Implementations</h3>
 *
 * <ul>
 *   <li>{@link ImmutableListMultimap}
 *   <li>{@link ImmutableSetMultimap}
 *   <li>Configure your own mutable multimap with {@link MultimapBuilder}
 *   <li>{@link LinkedListMultimap} (for one unusual kind of mutable {@code Multimap})
 * </ul>
 *
 * Guava contains a number of other multimap implementations, such as {@link ArrayListMultimap}. In

      AvlNode<E> newRoot = new AvlNode<>(element, occurrences);
      successor(header, newRoot, header);
      rootReference.checkAndSet(root, newRoot);
      return 0;
    }
    int[] result = new int[1]; // used as a mutable int reference to hold result
    AvlNode<E> newRoot = root.add(comparator(), element, occurrences, result);
    rootReference.checkAndSet(root, newRoot);
    return result[0];
  }

  @CanIgnoreReturnValue

        if (subgraph.nodes().contains(successorNode)) {
          subgraph.addEdge(node, successorNode, edge);
        }
      }
    }
    return subgraph;
  }

  /** Creates a mutable copy of {@code graph} with the same nodes and edges. */
  public static <N> MutableGraph<N> copyOf(Graph<N> graph) {
    MutableGraph<N> copy = GraphBuilder.from(graph).expectedNodeCount(graph.nodes().size()).build();

 * Immutable empty instances are returned for collection types; {@code ""} for string; {@code 0} for
 * number types; reasonable default instance for other stateless types. For mutable types, a fresh
 * instance is created each time {@code get()} is called.
 *
 * @author Kevin Bourrillion
 * @author Ben Yu
 * @since 12.0
 */
@GwtIncompatible
@J2ktIncompatible
@NullMarked

 */
@NullUnmarked
public abstract class AbstractGraphTest {

  Graph<Integer> graph;

  /**
   * The same reference as {@link #graph}, except as a mutable graph. This field is null in case
   * {@link #createGraph()} didn't return a mutable graph.
   */
  MutableGraph<Integer> graphAsMutableGraph;

  static final Integer N1 = 1;
  static final Integer N2 = 2;
  static final Integer N3 = 3;