checkNotNull(collection);
    return (collection instanceof EnumSet)
        ? EnumSet.complementOf((EnumSet<E>) collection)
        : makeComplementByHand(collection, type);
  }

  @J2ktIncompatible
  @GwtIncompatible
  private static <E extends Enum<E>> EnumSet<E> makeComplementByHand(
      Collection<E> collection, Class<E> type) {
    EnumSet<E> result = EnumSet.allOf(type);

import com.google.common.collect.testing.features.CollectionSize;
import com.google.common.testing.NullPointerTester;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.PriorityQueue;

import static java.util.Collections.sort;
import static org.junit.Assert.assertThrows;

import com.google.common.annotations.GwtIncompatible;
import com.google.common.collect.testing.features.CollectionFeature;
import com.google.common.collect.testing.features.CollectionSize;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

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

import javax.inject.Inject;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;

import org.apache.maven.artifact.AbstractArtifactComponentTestCase;

import com.google.common.collect.testing.features.CollectionSize;
import com.google.common.collect.testing.features.Feature;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;

/**
 * Tests for CompactHashSet.
 *

    @Override
    public Entry<K, Collection<V>>[] createArray(int length) {
      return (Entry<K, Collection<V>>[]) new Entry<?, ?>[length];
    }

    @Override
    public Iterable<Entry<K, Collection<V>>> order(List<Entry<K, Collection<V>>> insertionOrder) {
      Map<K, Collection<V>> map = new HashMap<>();
      List<Entry<K, V>> builder = new ArrayList<>();
      for (Entry<K, Collection<V>> entry : insertionOrder) {

 * limitations under the License.
 */

package com.google.common.collect.testing.features;

import static com.google.common.collect.testing.Helpers.copyToSet;
import static java.util.Collections.disjoint;
import static java.util.Collections.unmodifiableList;

import com.google.common.annotations.GwtIncompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.lang.annotation.Annotation;

package com.google.common.collect;

import static com.google.common.collect.BoundType.CLOSED;
import static com.google.common.truth.Truth.assertThat;
import static java.util.Arrays.asList;
import static java.util.Collections.sort;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;

import java.util.Collection;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Creates collections, containing sample elements, to be tested.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public interface TestCollectionGenerator<E extends @Nullable Object>

import java.io.File;
import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Properties;

import org.apache.maven.model.Model;
import org.apache.maven.model.v4.MavenStaxReader;
import org.apache.maven.model.v4.MavenStaxWriter;