@Override
        public ModelSource resolveModel(org.apache.maven.model.Dependency dependency)
                throws UnresolvableModelException {
            switch (dependency.getManagementKey()) {
                case BASE1_ID:
                    return new StringModelSource(BASE1);
                case BASE2_ID:
                    return new StringModelSource(BASE2);
            }

                        prefix, "optional", problems, errOn30, Version.V20, d.getOptional(), d.getManagementKey(), d);

                if (!management) {
                    validateVersion(
                            prefix, "version", problems, errOn30, Version.V20, d.getVersion(), d.getManagementKey(), d);

                    /*

            if (depMgmt != null) {
                for (Dependency dependency : depMgmt.getDependencies()) {
                    dependencies.put(dependency.getManagementKey(), dependency);
                }
            } else {
                depMgmt = DependencyManagement.newInstance();
            }

            Set<String> directDependencies = new HashSet<>(dependencies.keySet());

                Artifact managedArtifact = createDependencyArtifact(managedDependency, null, pomArtifact);

                managedVersions.put(managedDependency.getManagementKey(), managedArtifact);
            }
        }

        List<ArtifactRepository> aggregatedRepositories =
                aggregateRepositories(request.getRemoteRepositories(), pomRepositories);

        Map<String, Dependency> normalized = new LinkedHashMap<>(dependencies.size() * 2);

        for (Dependency dependency : dependencies) {
            normalized.put(dependency.getManagementKey(), dependency);
        }

        if (dependencies.size() != normalized.size()) {
            builder.dependencies(normalized.values());
        }

        return builder.build();
    }

                    .setMessage("'dependencyManagement.dependencies.dependency.groupId' for "
                            + dependency.getManagementKey() + " is missing.")
                    .setLocation(dependency.getLocation("")));
            return null;
        }
        if (artifactId == null || artifactId.isEmpty()) {

          <code>
            <![CDATA[
    private volatile String managementKey;

    /**
     * @return the management key as {@code groupId:artifactId:type}
     */
    public String getManagementKey() {
        if (managementKey == null) {
            managementKey = getGroupId() + ":" + getArtifactId() + ":" + getType() + (getClassifier() != null ? ":" + getClassifier() : "");
        }