}

    public static String key(String groupId, String artifactId, String version) {
        notBlank(groupId, "groupId can neither be null, empty nor blank");
        notBlank(artifactId, "artifactId can neither be null, empty nor blank");
        notBlank(version, "version can neither be null, empty nor blank");

        return groupId + ":" + artifactId + ":" + version;
    }

import static org.junit.jupiter.api.Assertions.assertNull;

class MavenModelMergerTest {
    private MavenModelMerger modelMerger = new MavenModelMerger();

    // modelVersion is neither inherited nor injected
    @Test
    void testMergeModel_ModelVersion() {
        Model parent = Model.newBuilder().modelVersion("4.0.0").build();
        Model model = Model.newInstance();

/**
 * Indicates whether an endpoint of some range is contained in the range itself ("closed") or not
 * ("open"). If a range is unbounded on a side, it is neither open nor closed on that side; the
 * bound simply does not exist.
 *
 * @since 10.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public enum BoundType {
  /** The endpoint value <i>is not</i> considered part of the set ("exclusive"). */
  OPEN(false),
  CLOSED(true);

  /**
   * Returns a {@code ContiguousSet} containing the same values in the given domain {@linkplain
   * Range#contains contained} by the range.
   *
   * @throws IllegalArgumentException if neither range nor the domain has a lower bound, or if
   *     neither has an upper bound
   * @since 13.0
   */
  public static <C extends Comparable> ContiguousSet<C> create(
      Range<C> range, DiscreteDomain<C> domain) {
    checkNotNull(range);

  /** Returns the cause for which the entry was removed. */
  public RemovalCause getCause() {
    return cause;
  }

  /**
   * Returns {@code true} if there was an automatic removal due to eviction (the cause is neither
   * {@link RemovalCause#EXPLICIT} nor {@link RemovalCause#REPLACED}).
   */
  public boolean wasEvicted() {
    return cause.wasEvicted();
  }

  private static final long serialVersionUID = 0;

   * array nor its contents can be null, but it is not useful to force the use of {@code
   * requireNonNull} or the like just to assert that.
   *
   * <p>{@code EqualsTester} will always check that every object it is given returns false from
   * {@code equals(null)}, so it is neither useful nor allowed to include a null value in any
   * equality group.
   */

/**
 * Indicates whether an endpoint of some range is contained in the range itself ("closed") or not
 * ("open"). If a range is unbounded on a side, it is neither open nor closed on that side; the
 * bound simply does not exist.
 *
 * @since 10.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public enum BoundType {
  /** The endpoint value <i>is not</i> considered part of the set ("exclusive"). */
  OPEN(false),
  CLOSED(true);

        // neither inherited nor injected
    }

    @Override
    protected void mergeModel_ArtifactId(
            Model.Builder builder, Model target, Model source, boolean sourceDominant, Map<Object, Object> context) {
        // neither inherited nor injected
    }

    @Override
    protected void mergeModel_Profiles(

   * <p>The returned set's {@link Object#toString} method returns a shorthand form of the set's
   * contents, such as {@code "[1..100]}"}.
   *
   * @throws IllegalArgumentException if neither this range nor the domain has a lower bound, or if
   *     neither has an upper bound
   */
  public ImmutableSortedSet<C> asSet(DiscreteDomain<C> domain) {
    checkNotNull(domain);
    if (isEmpty()) {
      return ImmutableSortedSet.of();

   * <p>The returned set's {@link Object#toString} method returns a shorthand form of the set's
   * contents, such as {@code "[1..100]}"}.
   *
   * @throws IllegalArgumentException if neither this range nor the domain has a lower bound, or if
   *     neither has an upper bound
   */
  public ImmutableSortedSet<C> asSet(DiscreteDomain<C> domain) {
    checkNotNull(domain);
    if (isEmpty()) {
      return ImmutableSortedSet.of();