putEdge(N1, N1);
    assertThat(graph.outDegree(N1)).isEqualTo(2);
    putEdge(N2, N1);
    assertThat(graph.outDegree(N1)).isEqualTo(3);
  }

  // Stable order tests

  // Note: Stable order means that the ordering doesn't change between iterations and versions.
  // Ideally, the ordering in test should never be updated.
  @Test
  public void stableIncidentEdgeOrder_edges_returnsInStableOrder() {

import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/** Tests for ordering the elements of graphs. */
@RunWith(JUnit4.class)
@NullUnmarked
public final class ElementOrderTest {
  // Node order tests

  @Test
  public void nodeOrder_none() {
    MutableGraph<Integer> graph = GraphBuilder.directed().nodeOrder(unordered()).build();

    assertThat(graph.nodeOrder()).isEqualTo(unordered());
  }

  @Test

    putEdge(N1, N1);
    assertThat(graph.outDegree(N1)).isEqualTo(2);
    putEdge(N2, N1);
    assertThat(graph.outDegree(N1)).isEqualTo(3);
  }

  // Stable order tests

  // Note: Stable order means that the ordering doesn't change between iterations and versions.
  // Ideally, the ordering in test should never be updated.
  @Test
  public void stableIncidentEdgeOrder_edges_returnsInStableOrder() {

  /**
   * Returns a {@code TopKSelector} that collects the lowest {@code k} elements added to it,
   * relative to the natural ordering of the elements, and returns them via {@link #topK} in
   * ascending order.
   *
   * @throws IllegalArgumentException if {@code k < 0} or {@code k > Integer.MAX_VALUE / 2}
   */
  public static <T extends Comparable<? super T>> TopKSelector<T> least(int k) {
    return least(k, Ordering.natural());

                    populateForRowKeySet(table, elements);
                    return table.rowKeySet();
                  }

                  @Override
                  public List<String> order(List<String> insertionOrder) {
                    sort(insertionOrder);
                    return insertionOrder;
                  }
                })
            .named("TreeBasedTable.rowKeySet")

                  public List<String> order(List<String> insertionOrder) {
                    List<String> order = new ArrayList<>();
                    for (String s : insertionOrder) {
                      int index = order.indexOf(s);
                      if (index == -1) {
                        order.add(s);
                      } else {
                        order.add(index, s);
                      }

   * TestContainerGenerator#order(List)}. Tests should use this method only if they declare
   * requirement {@link com.google.common.collect.testing.features.CollectionFeature#KNOWN_ORDER}.
   */
  protected List<E> getOrderedElements() {
    List<E> list = new ArrayList<>();
    for (E e : getSubjectGenerator().order(new ArrayList<E>(getSampleElements()))) {
      list.add(e);
    }

        super(buildMessage(message, problems), null);
        this.problems = problems;
    }

    /**
     * Formats message out of problems: problems are sorted (in natural order of {@link BuilderProblem.Severity})
     * and then a list is built. These exceptions are usually thrown in "fatal" cases (and usually prevent Maven
     * from starting), and these exceptions may end up very early on output.
     *

                  public List<String> order(List<String> insertionOrder) {
                    List<String> order = new ArrayList<>();
                    for (String s : insertionOrder) {
                      int index = order.indexOf(s);
                      if (index == -1) {
                        order.add(s);
                      } else {
                        order.add(index, s);
                      }

   * comes from a data structure supporting efficient indexed random access, typically an array or
   * list.
   *
   * <p>The order of the resulting stream is defined if and only if the order of the original stream
   * was defined.
   */
  public static <T extends @Nullable Object, R extends @Nullable Object> Stream<R> mapWithIndex(