class ProjectInheritanceTest extends AbstractProjectInheritanceTestCase {
    // ----------------------------------------------------------------------
    //
    // p4 inherits from p3
    // p3 inherits from p2
    // p2 inherits from p1
    // p1 inherits from p0
    // p0 inherits from super model
    //
    // or we can show it graphically as:
    //
    // p4 ---> p3 ---> p2 ---> p1 ---> p0 --> super model
    //

    }

    void addEdge(Vertex from, Vertex to) throws CycleDetectedException {
        from.children.add(to);
        to.parents.add(from);
        List<String> cycle = findCycle(to);
        if (cycle != null) {
            // remove edge which introduced cycle
            removeEdge(from, to);
            throw new CycleDetectedException(

        V20,
        V30,
        V31,
        V40
    }

    /**
     * Gets the identifier of the model from which the problem originated. While the general form of this identifier is
     * <code>groupId:artifactId:version</code> the returned identifier need not be complete. The identifier is derived
     * from the information that is available at the point the problem occurs and as such merely serves as a best effort

    /**
     * Merges values from the specified parent model into the given child model. Implementations are expected to keep
     * parent and child completely decoupled by injecting deep copies of objects into the child rather than the original
     * objects from the parent.
     *
     * @param child The child model into which to merge the values inherited from the parent, must not be
     *            <code>null</code>.

entity. "You" (or "Your") shall mean an individual or Legal Entity exercising permissions granted by this License. "Source" form shall mean the preferred form for making modifications, including but not limited to software source code, documentation source, and configuration files. "Object" form shall mean any form resulting from mechanical transformation or translation of a Source form, including but not limited to compiled object code, generated documentation, and conversions to other media types. "Work"...

        } catch (FileNotFoundException e) {
            throw new RepositoryMetadataReadException("Cannot read metadata from '" + mappingFile + "'", e);
        } catch (IOException | XMLStreamException e) {
            throw new RepositoryMetadataReadException(
                    "Cannot read metadata from '" + mappingFile + "': " + e.getMessage(), e);
        }
    }

    /**

    private void visit(MetadataGraphVertex from, List<MetadataGraphVertex> visited, MetadataGraph graph) {
        if (visited.contains(from)) {
            return;
        }

        visited.add(from);

        List<MetadataGraphEdge> exitList = graph.getExcidentEdges(from);
        // String s = "|---> "+from.getMd().toString()+" - "+(exitList == null ? -1 : exitList.size()) + " exit links";

     *            be {@code null}.
     * @param session The build session from which to pick the current project and repository settings, must not be
     *            {@code null}.
     * @param parent The parent class realm for the plugin, may be {@code null} to use the Maven core realm.
     * @param imports The packages/types to import from the parent realm, may be {@code null}.

    }

    @Override
    public List<Toolchain> getToolchains(Session session, String type, Map<String, String> requirements)
            throws ToolchainManagerException {
        MavenSession s = InternalMavenSession.from(session).getMavenSession();
        List<org.apache.maven.toolchain.Toolchain> toolchains =
                toolchainManagerPrivate.getToolchains(s, type, requirements);
        return new MappedList<>(toolchains, this::toToolchain);

     */
    String getArtifactId();

    /**
     * The repository from which the plugin prefix was resolved.
     *
     * @return The repository from which the plugin prefix was resolved or {@code null} if the prefix was resolved from
     *         the supplied POM.
     */
    ArtifactRepository getRepository();