Exclusion exclusion1 = new Exclusion();
        exclusion1.setGroupId("*");
        exclusion1.setArtifactId("maven-model");

        Exclusion exclusion2 = new Exclusion();
        exclusion2.setGroupId("org.apache.maven");
        exclusion2.setArtifactId("maven-core");

        ExclusionArtifactFilter filter = new ExclusionArtifactFilter(Arrays.asList(exclusion1, exclusion2));

            Set<String> exclusions = new LinkedHashSet<>();

            for (ClassRealm extensionRealm : extensionRealms) {
                List<String> excludes = exportedArtifacts.get(extensionRealm);

                if (excludes != null) {
                    exclusions.addAll(excludes);
                }

                .map(d -> mergeDependency(d, sourceIterator.next(), sourceDominant, context))
                .collect(Collectors.toList()));
    }

    @Override
    protected void mergeDependency_Exclusions(
            Dependency.Builder builder,
            Dependency target,
            Dependency source,
            boolean sourceDominant,
            Map<Object, Object> context) {
        // don't merge
    }

        <artifactId>plexus-container-default</artifactId>
        <version>${plexus.version}</version>
        <exclusions>
          <exclusion>
            <groupId>commons-logging</groupId>
            <artifactId>commons-logging-api</artifactId>
          </exclusion>
        </exclusions>
      </dependency>
    </dependencies>
  </dependencyManagement>

      <artifactId>maven-core-it-support</artifactId>
      <version>1.3</version>
      <scope>runtime</scope>
      <exclusions>
        <exclusion>
          <groupId>commons-lang</groupId>
          <artifactId>commons-lang</artifactId>
        </exclusion>
      </exclusions>
    </dependency>
  </dependencies>

        @Override
        protected void mergeDependency_Exclusions(
                Dependency.Builder builder,
                Dependency target,
                Dependency source,
                boolean sourceDominant,
                Map<Object, Object> context) {
            List<Exclusion> tgt = target.getExclusions();
            if (tgt.isEmpty()) {
                List<Exclusion> src = source.getExclusions();

                Dependency dependency = dependencies.get(key);
                Collection<Exclusion> exclusions = dependency != null ? dependency.getExclusions() : null;
                org.eclipse.aether.graph.Dependency dep = RepositoryUtils.toDependency(artifact, exclusions);
                if (!DependencyScope.SYSTEM.is(dep.getScope())
                        && dep.getArtifact().getFile() != null) {

    }

    private static boolean exclusionsEquals(List<Exclusion> a, List<Exclusion> b) {
        if (a.size() != b.size()) {
            return false;
        }

        Iterator<Exclusion> aI = a.iterator();
        Iterator<Exclusion> bI = b.iterator();

        while (aI.hasNext()) {
            Exclusion aD = aI.next();
            Exclusion bD = bI.next();

    @Override
    public Collection<Exclusion> getExclusions() {
        return new MappedCollection<>(dependency.getExclusions(), this::toExclusion);
    }

    private Exclusion toExclusion(org.eclipse.aether.graph.Exclusion exclusion) {
        return new Exclusion() {
            @Nullable
            @Override
            public String getGroupId() {
                return exclusion.getGroupId();
            }

            if (result.isEmpty()) {
                boolean isPlural = excludedProjects.size() > 1;
                String message = String.format(
                        "The project exclusion%s in --projects/-pl resulted in an "
                                + "empty reactor, please correct %s.",
                        isPlural ? "s" : "", isPlural ? "them" : "it");