Set<String> all = Sets.union(friends, enemies);
    assertEquals(5, all.size());

    ImmutableSet<String> immut = Sets.union(friends, enemies).immutableCopy();
    HashSet<String> mut = Sets.union(friends, enemies).copyInto(new HashSet<String>());

    enemies.add("Buck");
    assertEquals(6, all.size());
    assertEquals(5, immut.size());
    assertEquals(5, mut.size());
  }

            new TestStringSetGenerator() {
              @Override
              public Set<String> create(String[] elements) {
                return new HashSet<>(MinimalCollection.of(elements));
              }
            })
        .named("HashSet")
        .withFeatures(
            SetFeature.GENERAL_PURPOSE,
            CollectionFeature.SERIALIZABLE,
            CollectionFeature.ALLOWS_NULL_VALUES,

import com.google.common.collect.testing.testers.CollectionSerializationEqualTester;
import com.google.common.testing.SerializableTester;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import junit.framework.TestSuite;

/**

            new TestStringSetGenerator() {
              @Override
              public Set<String> create(String[] elements) {
                return new HashSet<>(MinimalCollection.of(elements));
              }
            })
        .named("HashSet")
        .withFeatures(
            SetFeature.GENERAL_PURPOSE,
            CollectionFeature.SERIALIZABLE,
            CollectionFeature.ALLOWS_NULL_VALUES,

            Collection<String> packages,
            String key,
            XmlNode configuration) {
        this.realm = realm;
        this.artifacts = Collections.unmodifiableSet(new HashSet<>(artifacts));
        this.packages = Collections.unmodifiableSet(new HashSet<>(packages));
        this.key = key;
        this.configuration = configuration;
    }

    /**
     * Returns ClassLoader used to load extension classes.
     */

    Set<String> all = Sets.union(friends, enemies);
    assertEquals(5, all.size());

    ImmutableSet<String> immut = Sets.union(friends, enemies).immutableCopy();
    HashSet<String> mut = Sets.union(friends, enemies).copyInto(new HashSet<String>());

    enemies.add("Buck");
    assertEquals(6, all.size());
    assertEquals(5, immut.size());
    assertEquals(5, mut.size());
  }

import com.google.common.collect.testing.testers.CollectionSerializationEqualTester;
import com.google.common.testing.SerializableTester;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import junit.framework.TestSuite;

/**

 */
package org.apache.maven;

import javax.inject.Inject;
import javax.inject.Named;
import javax.inject.Singleton;

import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.Set;

import org.apache.maven.artifact.Artifact;
import org.apache.maven.artifact.ArtifactUtils;

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

import java.util.Collections;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import org.codehaus.plexus.classworlds.realm.ClassRealm;

import static java.util.function.Function.identity;
import static java.util.stream.Collectors.collectingAndThen;

        this.scopes = new HashSet<>();

        addScopes(scopes);
    }

    /**
     * Creates a new filter that combines the specified filters.
     *
     * @param filters The filters to combine, may be {@code null}.
     */
    public CumulativeScopeArtifactFilter(CumulativeScopeArtifactFilter... filters) {
        this.scopes = new HashSet<>();

        if (filters != null) {