} else {
            metadataMap.put(metadata.getKey(), metadata);
        }
    }

    @Override
    public Collection<ArtifactMetadata> getMetadataList() {
        if (metadataMap == null) {
            return Collections.emptyList();
        }

        return Collections.unmodifiableCollection(metadataMap.values());
    }

    // ----------------------------------------------------------------------

import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import org.junit.Before;
import org.junit.Test;

public class ReadingConverterTest {

    private ReadingConverter converter;
    private TestReadingConverter testConverter;

  }

  private static <E> ImmutableList<E> copyFromCollection(Collection<? extends E> collection) {
    Object[] elements = collection.toArray();
    switch (elements.length) {
      case 0:
        return of();
      case 1:
        @SuppressWarnings("unchecked") // safe because it came from `collection`
        E element = (E) elements[0];
        return of(element);
      default:

    @Override
    public Set<String> keySet() {
        return parent.keySet();
    }

    /**
     * Returns a Collection view of the values contained in this map.
     *
     * @return a collection view of the values contained in this map
     */
    @Override
    public Collection<Object> values() {
        return parent.values();
    }

    /**

import com.google.common.collect.testing.features.CollectionFeature;
import com.google.common.testing.SerializableTester;
import java.io.Serializable;
import java.lang.reflect.Method;
import java.util.Collections;
import java.util.List;
import org.junit.Ignore;

/**
 * Tests for the {@code inverse} view of a BiMap.
 *
 * <p>This assumes that {@code bimap.inverse().inverse() == bimap}, which is not technically

 * 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 java.util.Collection;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

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

import static com.google.common.graph.GraphConstants.EXPECTED_DEGREE;

import com.google.common.collect.BiMap;
import com.google.common.collect.HashBiMap;
import com.google.common.collect.ImmutableBiMap;
import java.util.Collections;
import java.util.Map;
import java.util.Set;

/**
 * An implementation of {@link NetworkConnections} for undirected networks.
 *
 * @author James Sexton
 * @param <N> Node parameter type

   *     to primitives
   * @throws NullPointerException if {@code collection} or any of its elements is null
   * @since 1.0 (parameter was {@code Collection<Long>} before 12.0)
   */
  public static long[] toArray(Collection<? extends Number> collection) {
    if (collection instanceof LongArrayAsList) {
      return ((LongArrayAsList) collection).toLongArray();
    }

 *
 * <p>The collections returned by {@link #keySet()} and {@link #asMap()} iterate through the keys in
 * the order they were first added to the multimap. Similarly, {@link #get}, {@link #removeAll}, and
 * {@link #replaceValues} return collections that iterate through the values in the order they were
 * added. The collections generated by {@link #entries()}, {@link #keys()}, and {@link #values}