*/
    @Deprecated(since = "4.0.0")
    public Set<MavenProject> getOptionalProjectsBySelectors(
            MavenExecutionRequest request, List<MavenProject> projects, Set<String> projectSelectors) {
        Set<MavenProject> resolvedOptionalProjects = new LinkedHashSet<>();
        Set<String> unresolvedOptionalSelectors = new HashSet<>();

              @Override
              public SortedSet<String> create(String[] elements) {
                SortedSet<String> set = new TreeSet<>(arbitraryNullFriendlyComparator());
                Collections.addAll(set, elements);
                return set;
              }
            })
        .named("TreeSet, with comparator")
        .withFeatures(
            SetFeature.GENERAL_PURPOSE,

              .withTearDown(parentBuilder.getTearDown())
              .createTestSuite());
    }

    return derived;
  }

  private static Set<Feature<?>> computeInverseFeatures(Set<Feature<?>> mapFeatures) {
    Set<Feature<?>> inverseFeatures = new HashSet<>(mapFeatures);

    boolean nullKeys = inverseFeatures.remove(MapFeature.ALLOWS_NULL_KEYS);

import com.google.common.collect.testing.features.CollectionFeature;
import com.google.common.collect.testing.features.CollectionSize;
import java.util.Collection;
import java.util.Set;
import org.junit.Ignore;

/**
 * Tests {@link java.util.Set#equals}.
 *
 * @author George van den Driessche
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")

import com.google.common.collect.testing.features.CollectionFeature;
import com.google.common.collect.testing.features.CollectionSize;
import java.util.Collection;
import java.util.Set;
import org.junit.Ignore;

/**
 * Tests {@link java.util.Set#equals}.
 *
 * @author George van den Driessche
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")

  }

  public void testFrequency_set() {
    Set<String> set = newHashSet("a", "b", "c");
    assertEquals(1, frequency(set, "a"));
    assertEquals(1, frequency(set, "b"));
    assertEquals(1, frequency(set, "c"));
    assertEquals(0, frequency(set, "d"));
    assertEquals(0, frequency(set, 4.2));
    assertEquals(0, frequency(set, null));
  }

  public void testFrequency_list() {

  private Set<N> predecessorsOrEmpty(N node) {
    if (edgeType == EdgeType.INCOMING || edgeType == EdgeType.BOTH) {
      return graph.predecessors(node);
    } else {
      return ImmutableSet.of();
    }
  }

  /**
   * Returns the successors of the given node, or an empty set if this set does not represent
   * outgoing edges.
   */
  private Set<N> successorsOrEmpty(N node) {

import java.util.Set;

/**
 * Optional features of classes derived from {@code Set}.
 *
 * @author George van den Driessche
 */
@SuppressWarnings("rawtypes") // maybe avoidable if we rework the whole package?
@GwtCompatible
public enum SetFeature implements Feature<Set> {
  GENERAL_PURPOSE(CollectionFeature.GENERAL_PURPOSE);

  private final Set<Feature<? super Set>> implied;

    super(type, true, contents);
  }

  /*
   * equals() and hashCode() are more specific in the Set contract.
   */

  @Override
  public boolean equals(@Nullable Object object) {
    if (object instanceof Set) {
      Set<?> that = (Set<?>) object;
      return (this.size() == that.size()) && this.containsAll(that);
    }
    return false;
  }

  @Override

    super(type, true, contents);
  }

  /*
   * equals() and hashCode() are more specific in the Set contract.
   */

  @Override
  public boolean equals(@Nullable Object object) {
    if (object instanceof Set) {
      Set<?> that = (Set<?>) object;
      return (this.size() == that.size()) && this.containsAll(that);
    }
    return false;
  }

  @Override