* exercise null handling fail on those subcollections.
   */
  public abstract static class NullsBefore implements Comparator<@Nullable String>, Serializable {
    /*
     * We don't serialize this class in GWT, so we don't care about whether GWT will serialize this
     * field.
     */
    @GwtTransient private final String justAfterNull;

    protected NullsBefore(String justAfterNull) {
      if (justAfterNull == null) {

  }

  public void testCheckElementIndex_badSize() {
    try {
      Preconditions.checkElementIndex(1, -1);
      fail();
    } catch (IllegalArgumentException expected) {
      // don't care what the message text is, as this is an invalid usage of
      // the Preconditions class, unlike all the other exceptions it throws
    }
  }

  public void testCheckElementIndex_negative() {
    try {

   * all elements that are contained by {@code set1} and not contained by {@code set2}. {@code set2}
   * may also contain elements not present in {@code set1}; these are simply ignored. The iteration
   * order of the returned set matches that of {@code set1}.
   *
   * <p>Results are undefined if {@code set1} and {@code set2} are sets based on different

 * all components from this class, and the upfront construction taken care of entirely by the {@link ProjectBuilder}.
 * There is still the issue of having to run the lifecycle in order to find all the compile source roots and resource
 * directories but I hope to take care of this during the Maven 4.0 release (jvz).
 * </p>
 */
public class MavenProject implements Cloneable {

     * by concurrently running mojo executions. To prevent race conditions, an aggregating execution will block
     * all other executions until finished.
     * We also lock on a given project to forbid a forked lifecycle to be executed concurrently with the project.
     * TODO: ideally, the builder should take care of the ordering in a smarter way

        toolchainModels.put("rare", Collections.singletonList(new ToolchainModel()));
        executionRequest.setToolchains(toolchainModels);
        when(session.getRequest()).thenReturn(executionRequest);

        List<Toolchain> toolchains = toolchainManager.getToolchains(session, "rare", null);

        assertEquals(1, toolchains.size());
    }

    @Test

        List<ToolchainModel> rareToolchains = new ArrayList<>();
        ToolchainModel rareToolchainModel = new ToolchainModel();
        rareToolchainModel.setType("rare");
        rareToolchains.add(rareToolchainModel);
        groupedToolchains.put("rare", rareToolchains);

        // execute
        ToolchainPrivate[] toolchains = toolchainManager.getToolchainsForType("basic", session);

        // verify

    g2.addEdge(N1, N3, E12);

    assertThat(network).isNotEqualTo(g2);
  }

  // Node/edge sets and node/edge connections are the same, but network properties differ.
  // (In this case the networks are considered equivalent; the property differences are irrelevant.)
  @Test
  public void equivalent_propertiesDiffer() {
    network.addEdge(N1, N2, E12);

    MutableNetwork<Integer, String> g2 =

    g2.putEdge(N1, N1);

    assertThat(graph).isNotEqualTo(g2);
  }

  // Node/edge sets and node/edge connections are the same, but graph properties differ.
  // In this case the graphs are considered equivalent; the property differences are irrelevant.
  @Test
  public void equivalent_propertiesDiffer() {
    graph.putEdge(N1, N2);

    MutableGraph<Integer> g2 =

  }

  /**
   * Returns a contiguous set containing all {@code int} values from {@code lower} (inclusive) to
   * {@code upper} (exclusive). If the endpoints are equal, an empty set is returned. (These are the
   * same values contained in {@code Range.closedOpen(lower, upper)}.)
   *
   * @throws IllegalArgumentException if {@code lower} is greater than {@code upper}
   * @since 23.0
   */