checkNotNull(elements);
      if (elements instanceof Collection) {
        Collection<?> collection = (Collection<?>) elements;
        ensureRoomFor(collection.size());
        if (collection instanceof ImmutableCollection) {
          ImmutableCollection<?> immutableCollection = (ImmutableCollection<?>) collection;
          size = immutableCollection.copyIntoArray(contents, size);
          return this;

  static boolean removeAllImpl(Multiset<?> self, Collection<?> elementsToRemove) {
    Collection<?> collection =
        (elementsToRemove instanceof Multiset)
            ? ((Multiset<?>) elementsToRemove).elementSet()
            : elementsToRemove;

    return self.elementSet().removeAll(collection);
  }

  /** An implementation of {@link Multiset#retainAll}. */

  public void testCopyOf_shortcut_empty() {
    Collection<String> c = ImmutableMultiset.of();
    assertSame(c, ImmutableMultiset.copyOf(c));
  }

  public void testCopyOf_shortcut_singleton() {
    Collection<String> c = ImmutableMultiset.of("a");
    assertSame(c, ImmutableMultiset.copyOf(c));
  }

  public void testCopyOf_shortcut_immutableMultiset() {
    Collection<String> c = ImmutableMultiset.of("a", "b", "c");

  public void testRetainAll_duplicatesKept() {
    E[] array = createSamplesArray();
    array[1] = e0();
    collection = getSubjectGenerator().create(array);
    assertFalse(
        "containsDuplicates.retainAll(superset) should return false",
        collection.retainAll(MinimalCollection.of(createSamplesArray())));
    expectContents(array);
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)

 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.api.services;

import java.nio.file.Path;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Objects;

import org.apache.maven.api.RemoteRepository;
import org.apache.maven.api.Session;
import org.apache.maven.api.annotations.Experimental;

  @CollectionSize.Require(absent = {ZERO, ONE})
  public void testCreateWithDuplicates_nullDuplicatesNotRejected() {
    E[] array = createArrayWithNullElement();
    array[0] = null;
    collection = getSubjectGenerator().create(array);

    List<E> expectedWithDuplicateRemoved = asList(array).subList(1, getNumElements());
    expectContents(expectedWithDuplicateRemoved);
  }

package org.apache.maven.repository.internal;

import java.util.stream.Collectors;

import org.apache.maven.model.Plugin;
import org.eclipse.aether.RequestTrace;
import org.eclipse.aether.collection.CollectRequest;
import org.eclipse.aether.collection.CollectStepData;
import org.eclipse.aether.resolution.ArtifactDescriptorRequest;
import org.eclipse.aether.resolution.ArtifactRequest;
import org.eclipse.aether.resolution.DependencyRequest;

/**

  @CollectionSize.Require(absent = {ZERO, ONE})
  public void testCreateWithDuplicates_nullDuplicatesNotRejected() {
    E[] array = createArrayWithNullElement();
    array[0] = null;
    collection = getSubjectGenerator().create(array);

    List<E> expectedWithDuplicateRemoved = asList(array).subList(1, getNumElements());
    expectContents(expectedWithDuplicateRemoved);
  }

  private void assertCollectionSize(Collection<?> collection, int size) {
    assertThat(collection.size()).isEqualTo(size);
    if (size > 0) {
      assertThat(collection.isEmpty()).isFalse();
    } else {
      assertThat(collection.isEmpty()).isTrue();
    }
    assertThat(Iterables.size(collection)).isEqualTo(size);
    assertThat(Iterators.size(collection.iterator())).isEqualTo(size);
  }

    }

    protected TermsQueryBuilder regTermsQ(String name, Collection<?> values) {
        checkEsInvalidQueryCollection(name, values);
        TermsQueryBuilder termsQuery = QueryBuilders.termsQuery(name, values);
        regQ(termsQuery);
        return termsQuery;
    }

    protected IdsQueryBuilder regIdsQ(Collection<String> values) {
        checkEsInvalidQueryCollection("_id", values);