*/
@Deprecated(since = "4.0.0")
public class MavenToolchainMerger {

    public void merge(PersistedToolchains dominant, PersistedToolchains recessive, String recessiveSourceLevel) {
        if (dominant == null || recessive == null) {
            return;
        }

        recessive.setSourceLevel(recessiveSourceLevel);

        shallowMerge(dominant.getToolchains(), recessive.getToolchains(), recessiveSourceLevel);
    }

  /**
   * Returns the tag attached with [type] as a key, or null if no tag is attached with that key.
   *
   * The tags on a call are seeded from the [request tags][Request.tag]. This set will grow if new
   * tags are computed.
   */
  fun <T : Any> tag(type: KClass<T>): T?

  /**
   * Returns the tag attached with [type] as a key, or null if no tag is attached with that key.
   *

                .installationToolchainsSource(
                        installationToolchainsFile != null && Files.exists(installationToolchainsFile)
                                ? Sources.fromPath(installationToolchainsFile)
                                : null)
                .userToolchainsSource(
                        userToolchainsPath != null && Files.exists(userToolchainsPath)

    assertTrue("add(null) should return true", collection.add(null));
    expectAdded((E) null);
  }

  @CollectionFeature.Require(value = SUPPORTS_ADD, absent = ALLOWS_NULL_VALUES)
  public void testAdd_nullUnsupported() {
    assertThrows(NullPointerException.class, () -> collection.add(null));
    expectUnchanged();
    expectNullMissingWhenNullUnsupported("Should not contain null after unsupported add(null)");
  }

     * without requiring the XML to be parsed. For build sources, this typically
     * returns {@code null} since the coordinates are determined by parsing the POM.
     *
     * @return the model identifier, or {@code null} if not available or not applicable
     * @since 4.0.0
     */
    @Nullable
    default String getModelId() {
        return null;
    }

    /**
     * Interface for locating POM files within a project structure.

    assertTrue("add(null) should return true", collection.add(null));
    expectAdded((E) null);
  }

  @CollectionFeature.Require(value = SUPPORTS_ADD, absent = ALLOWS_NULL_VALUES)
  public void testAdd_nullUnsupported() {
    assertThrows(NullPointerException.class, () -> collection.add(null));
    expectUnchanged();
    expectNullMissingWhenNullUnsupported("Should not contain null after unsupported add(null)");
  }

        MavenSession session = new MavenSession(
                getContainer(), repoSession, new DefaultMavenExecutionRequest(), new DefaultMavenExecutionResult());
        session.setSession(defaultSessionFactory.newSession(session));

        DefaultSession s = new DefaultSession(session, null, null, null, null, null);

    @BeforeEach
    void setUp() throws Exception {
        policy = new DefaultGraphConflictResolutionPolicy();
        e1 = new MetadataGraphEdge("1.1", true, null, null, 2, 1);
        e2 = new MetadataGraphEdge("1.2", true, null, null, 3, 2);
        e3 = new MetadataGraphEdge("1.2", true, null, null, 2, 3);
    }

    // ------------------------------------------------------------------------------------------
    @Test

     * an empty string that by definition denotes the super POM.
     *
     * @return The model identifiers from the lineage of models, never {@code null}.
     */
    List<String> getModelIds();

    /**
     * Gets the assembled model.
     *
     * @return The assembled model, never {@code null}.
     */
    Model getEffectiveModel();

    /**

        if (includes != null) {
            includes = substVars(includes, INCLUDES_PROPERTY, configProps, callback);
            StringTokenizer st = new StringTokenizer(includes, "?\",", true);
            if (st.countTokens() > 0) {
                String location;
                do {
                    location = nextLocation(st);
                    if (location != null) {
                        boolean mandatory = true;