throws ArtifactMetadataRetrievalException {
        Set<Artifact> dependencies = new HashSet<>();

        if ("g".equals(artifact.getArtifactId())) {
            Artifact a = null;
            try {
                a = factory.createBuildArtifact("org.apache.maven", "h", "1.0", "jar");
                dependencies.add(a);
            } catch (Exception e) {

     *
     * @param relPath is the path of the requested model source relative to this model source POM.
     * @return related model source or <code>null</code> if no such model source.
     */
    ModelSource2 getRelatedSource(String relPath);

    /**
     * Returns location of the POM, never <code>null</code>.
     */
    URI getLocationURI();

  @CheckForNull
  public E lower(E element) {
    int index = headIndex(element, false) - 1;
    return (index == -1) ? null : elements.get(index);
  }

  @Override
  @CheckForNull
  public E floor(E element) {
    int index = headIndex(element, true) - 1;
    return (index == -1) ? null : elements.get(index);
  }

  @Override
  @CheckForNull
  public E ceiling(E element) {

  }

  @SuppressWarnings("unchecked")
  // if sortedSet.comparator() is null, the set must be naturally ordered
  public static <E extends @Nullable Object> Comparator<? super E> comparator(
      SortedSet<E> sortedSet) {
    Comparator<? super E> result = sortedSet.comparator();
    if (result == null) {
      result = (Comparator<? super E>) Ordering.natural();
    }
    return result;
  }

    /**
     * Builds the toolchains model from the configured toolchain files.
     *
     * @param userToolchainsFile The path to the toolchains file, may be <code>null</code> to disable parsing.
     * @return The toolchains model or <code>null</code> if no toolchain file was configured or the configured file does
     *         not exist.
     * @throws MisconfiguredToolchainException If the toolchain file exists but cannot be parsed.

     * modifications don't affect future retrievals of the super POM.
     *
     * @param version The model version to retrieve the super POM for (e.g. "4.0.0"), must not be {@code null}.
     * @return The super POM, never {@code null}.
     */
    Model getSuperModel(String version);

     *
     * @param effectiveToolchains the merged toolchains, may not be {@code null}
     * @param problems the problems while building the effectiveToolchains, if any.
     */
    public DefaultToolchainsBuildingResult(PersistedToolchains effectiveToolchains, List<Problem> problems) {
        this.effectiveToolchains = effectiveToolchains;
        this.problems = (problems != null) ? problems : new ArrayList<>();
    }

    @Override

            }
        }
        return matches;
    }

    protected Element getChild(Element element, String childName) {
        Element child = findChild(element, childName);
        if (child != null) {
            return child;
        }
        throw new RuntimeException(String.format("No <%s> element found in <%s>", childName, element.getTagName()));
    }

        if (server != null) {
            buf.append(server);
            if (port > 0) {
                buf.append(':');
                buf.append(port);
            }
            buf.append('/');
        }
        return buf.toString();
    }

    public NtlmPasswordAuthentication getAuthentication() {
        return new NtlmPasswordAuthentication(domain == null ? "" : domain, username, password);
    }

    checkNotNull(updaterFunction);
    Long result =
        map.compute(
            key,
            (k, value) -> updaterFunction.applyAsLong((value == null) ? 0L : value.longValue()));
    return requireNonNull(result);
  }

  /**
   * Updates the value currently associated with {@code key} with the specified function, and