return Collections.unmodifiableCollection(collection);
  }

  @Override
  public void clear() {
    // Clear each collection, to make previously returned collections empty.
    for (Collection<V> collection : map.values()) {
      collection.clear();
    }
    map.clear();
    totalSize = 0;
  }

  // Views

  /**
   * {@inheritDoc}
   *

    }
    return derivedSuites;
  }

  private static final class ReserializedSetGenerator<E> implements TestSetGenerator<E> {
    final OneSizeTestContainerGenerator<Collection<E>, E> gen;

    private ReserializedSetGenerator(OneSizeTestContainerGenerator<Collection<E>, E> gen) {
      this.gen = gen;
    }

    @Override
    public SampleElements<E> samples() {
      return gen.samples();
    }

    @Override

      @SuppressWarnings("unchecked")
      V[] valuesArray = (V[]) elements;

      // Start with a suitably shaped collection of entries
      Collection<Entry<K, V>> originalEntries = mapGenerator.getSampleElements(elements.length);

      // Create a copy of that, with the desired value for each value
      Collection<Entry<K, V>> entries = new ArrayList<>(elements.length);
      int i = 0;
      for (Entry<K, V> entry : originalEntries) {

   * elements than the collection), the element in the array immediately following the end of the
   * collection is set to {@code null}. This is useful in determining the length of the collection
   * <i>only</i> if the caller knows that the collection does not contain any null elements.
   *
   * <p>This method returns the elements in the order they are returned by the collection's
   * iterator.
   *

  public void testForEachUnknownOrder() {
    List<E> elements = new ArrayList<>();
    collection.forEach(elements::add);
    Helpers.assertEqualIgnoringOrder(asList(createSamplesArray()), elements);
  }

  @CollectionFeature.Require(KNOWN_ORDER)
  public void testForEachKnownOrder() {
    List<E> elements = new ArrayList<>();
    collection.forEach(elements::add);
    List<E> expected = Helpers.copyToList(getOrderedElements());

    return emptySet();
  }

  protected Collection<Method> suppressForConcurrentLinkedQueue() {
    return emptySet();
  }

  protected Collection<Method> suppressForLinkedBlockingDeque() {
    return emptySet();
  }

  protected Collection<Method> suppressForLinkedBlockingQueue() {
    return emptySet();
  }

    assertPermutationsCount(1, Collections2.permutations(Collections.<Integer>emptyList()));
    assertPermutationsCount(1, Collections2.permutations(newArrayList(1)));
    assertPermutationsCount(2, Collections2.permutations(newArrayList(1, 2)));
    assertPermutationsCount(6, Collections2.permutations(newArrayList(1, 2, 3)));
    assertPermutationsCount(5040, Collections2.permutations(newArrayList(1, 2, 3, 4, 5, 6, 7)));

 * under the License.
 */
package org.apache.maven.model.building;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

import static java.util.Collections.singleton;
import static org.apache.maven.model.building.ModelProblem.Severity.ERROR;
import static org.apache.maven.model.building.ModelProblem.Severity.FATAL;

/**

  /**
   * For documenting collections that support no optional features, such as {@link
   * java.util.Collections#emptySet}
   */
  NONE;

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

  CollectionFeature(Feature<? super Collection>... implied) {
    this.implied = copyToSet(implied);
  }

  @Override
  public Set<Feature<? super Collection>> getImpliedFeatures() {
    return implied;

        }
    }

    /**
     * chains a collection of {@link WorkspaceReader}s
     * @param workspaceReaderCollection the collection of readers, might be empty but never <code>null</code>
     * @return if the collection contains only one item returns the single item, otherwise creates a new
     *         {@link MavenChainedWorkspaceReader} chaining all readers in the order of the given collection.
     */