ImmutableSortedSet<Integer> asSet = RANGE_SET_ONE.asSet(DiscreteDomain.integers());
    assertEquals(expectedSet, asSet);
    assertThat(asSet).containsExactlyElementsIn(expectedSet).inOrder();
    assertTrue(asSet.containsAll(expectedSet));
    SerializableTester.reserializeAndAssert(asSet);
  }

  public void testAsSetHeadSet() {

    assertEmpty(getMultiset());
  }

  /**
   * Returns {@link Method} instances for the read tests that assume multisets support duplicates so
   * that the test of {@code Multisets.forSet()} can suppress them.
   */
  @J2ktIncompatible
  @GwtIncompatible // reflection
  public static List<Method> getElementSetDuplicateInitializingMethods() {
    return Arrays.asList(
        Helpers.getMethod(

        // in first step get parameter names of current goal
        Set<String> parametersNamesGoal = mojoDescriptor.getParameters().stream()
                .flatMap(this::getParameterNames)
                .collect(Collectors.toSet());

        Set<String> unknownParameters = getUnknownParameters(mojoExecution, parametersNamesGoal);

        if (unknownParameters.isEmpty()) {
            return;
        }

    Set<String> expected = Collections.singleton("a");
    assertEquals(expected, Optional.of("a").asSet());
  }

  public void testAsSet_absent() {
    assertTrue("Returned set should be empty", Optional.absent().asSet().isEmpty());
  }

  public void testAsSet_presentIsImmutable() {
    Set<String> presentAsSet = Optional.of("a").asSet();
    try {
      presentAsSet.add("b");
      fail();

import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.function.Predicate;

import static java.util.stream.Collectors.toSet;

/**
 * Container for storing the request from the user to activate or de-activate certain profiles and optionally fail the
 * build if those profiles do not exist.
 */
public class ProfileActivation {

import org.eclipse.sisu.Nullable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.slf4j.helpers.MessageFormatter;

import static java.util.stream.Collectors.toSet;

/**
 */
@Named
@Singleton
public class DefaultMaven implements Maven {
    private final Logger logger = LoggerFactory.getLogger(getClass());

    private final Lookup lookup;

      }
    }.test();
  }

  /**
   * Returns {@link Method} instances for the tests that assume multisets support duplicates so that
   * the test of {@code Multisets.forSet()} can suppress them.
   */
  @J2ktIncompatible
  @GwtIncompatible // reflection
  public static List<Method> getIteratorDuplicateInitializingMethods() {
    return Arrays.asList(

                        d.getGroupId() + ":" + d.getArtifactId()))
                .map(Artifact::getVersion)
                .collect(Collectors.toSet());

        if (mavenVersions.size() > 1) {
            pluginValidationManager.reportPluginValidationIssue(
                    PluginValidationManager.IssueLocality.EXTERNAL,
                    session,

        if (fieldSet == null) {
            fieldSet = split(getIndexAdminArrayFields(), ",")
                    .get(stream -> stream.filter(StringUtil::isNotBlank).map(String::trim).collect(Collectors.toSet()));
            propMap.put(INDEX_ADMIN_ARRAY_FIELD_SET, fieldSet);
        }
        return fieldSet;
    }

    default boolean validateIndexArrayFields(final Map<String, Object> source) {

        supplier.get(), "use Optional.orNull() instead of a Supplier that returns null");
  }

  @Override
  @CheckForNull
  public T orNull() {
    return null;
  }

  @Override
  public Set<T> asSet() {
    return Collections.emptySet();
  }

  @Override
  public <V> Optional<V> transform(Function<? super T, V> function) {
    checkNotNull(function);
    return Optional.absent();
  }

  @Override