*
 * @author Louis Wasserman
 */
@GwtCompatible
@NullMarked
public class MoreCollectorsTest extends TestCase {
  public void testToOptionalEmpty() {
    assertThat(Stream.empty().collect(toOptional())).isEmpty();
  }

  public void testToOptionalSingleton() {
    assertThat(Stream.of(1).collect(toOptional())).hasValue(1);
  }

  public void testToOptionalNull() {

    public MavenExecutionResult addException(Throwable t) {
        exceptions.add(t);

        return this;
    }

    @Override
    public boolean hasExceptions() {
        return !getExceptions().isEmpty();
    }

    @Override
    public BuildSummary getBuildSummary(MavenProject project) {
        return buildSummaries.get(project);
    }

    @Override

import static java.text.DateFormat.SHORT;
import static java.text.DateFormat.getDateInstance;
import static org.codelibs.core.collection.MultiIterator.iterable;
import static org.codelibs.core.lang.StringUtil.isEmpty;
import static org.codelibs.core.lang.StringUtil.isNotEmpty;
import static org.codelibs.core.misc.AssertionUtil.assertArgumentNotNull;

import java.text.DateFormat;
import java.text.ParsePosition;

                    dominantPluginGroupIds.add(pluginGroupId);
                }
            }
        }

        if (dominant.getLocalRepository() == null
                || dominant.getLocalRepository().isEmpty()) {
            dominant.setLocalRepository(recessive.getLocalRepository());
        }

        shallowMergeById(dominant.getMirrors(), recessive.getMirrors(), recessiveSourceLevel);

    assertFalse(multimap.containsValue(1));
    assertFalse(multimap.containsEntry("foo", 1));
    assertTrue(multimap.entries().isEmpty());
    assertTrue(multimap.equals(HashMultimap.create()));
    assertEquals(emptySet(), multimap.get("foo"));
    assertEquals(0, multimap.hashCode());
    assertTrue(multimap.isEmpty());
    assertEquals(HashMultiset.create(), multimap.keys());
    assertEquals(emptySet(), multimap.keySet());

  public void testEmptyMap() {
    Map<Character, String> map = ImmutableMap.of();
    ArrayBasedEscaperMap fem = ArrayBasedEscaperMap.create(map);
    // Non-null array of zero length.
    assertThat(fem.getReplacementArray()).isEmpty();
  }

  public void testMapLength() {
    Map<Character, String> map =
        ImmutableMap.of(
            'a', "first",
            'z', "last");

            versions.addAll(versioning.getVersions());
            versioning.setVersions(new ArrayList<>(versions));
        }

        // just carry-on as-is
        if (!recessive.getPlugins().isEmpty()) {
            metadata.setPlugins(new ArrayList<>(recessive.getPlugins()));
        }
    }

    public Object getKey() {
        return getGroupId() + ':' + getArtifactId();
    }

    for (K k : multimap().keySet()) {
      assertTrue(multimap().containsKey(k));
    }
  }

  public void testContainsKeyAgreesWithGet() {
    for (K k : sampleKeys()) {
      assertEquals(!multimap().get(k).isEmpty(), multimap().containsKey(k));
    }
  }

  public void testContainsKeyAgreesWithAsMap() {
    for (K k : sampleKeys()) {
      assertEquals(multimap().containsKey(k), multimap().asMap().containsKey(k));
    }
  }

  public UnmodifiableIterator<C> descendingIterator() {
    return emptyIterator();
  }

  @Override
  boolean isPartialView() {
    return false;
  }

  @Override
  public boolean isEmpty() {
    return true;
  }

  @Override
  public ImmutableList<C> asList() {
    return ImmutableList.of();
  }

  @Override
  public String toString() {
    return "[]";
  }

   */
  @CanIgnoreReturnValue
  public @Nullable E pollLast() {
    return isEmpty() ? null : removeAndGet(getMaxElementIndex());
  }

  /**
   * Removes and returns the greatest element of this queue.
   *
   * @throws NoSuchElementException if the queue is empty
   */
  @CanIgnoreReturnValue
  public E removeLast() {
    if (isEmpty()) {
      throw new NoSuchElementException();
    }