problems,
                            BuilderProblem.Severity.ERROR,
                            "pluginGroups.pluginGroup[" + i + "]",
                            null,
                            "must denote a valid group id and match the pattern " + ID);
                }
            }
        }

        List<Server> servers = settings.getServers();

        if (servers != null) {

     *
     * @param session the {@link Session}, must not be {@code null}
     * @param globalToolchainsSource The {@link Source} pointing to the global toolchains, must not be {@code null}
     * @param userToolchainsSource The {@link Source} pointing to the user toolchains, must not be {@code null}
     * @throws ToolchainsBuilderException if the project cannot be created

     * the returned model and must not rely on the input model being updated.
     *
     * @param model The model to interpolate, must not be {@code null}.
     * @param projectDir The project directory, may be {@code null} if the model does not belong to a local project but
     *            to some artifact's metadata.
     * @param request The model building request that holds further settings, must not be {@code null}.

    }

    /**
     * Validate the specified settings.
     *
     * @param settings The settings to validate, must not be {@code null}.
     * @return The list of problems that were encountered, must not be {@code null}.
     */
    @Nonnull
    default List<BuilderProblem> validate(@Nonnull Settings settings) {
        return validate(settings, false);
    }

     * has a current project, its plugin repositories will be used as well.
     *
     * @param plugin The plugin for which to resolve a version, must not be {@code null}.
     * @param session The Maven session to use, must not be {@code null}.
     */
    public DefaultPluginVersionRequest(Plugin plugin, MavenSession session) {
        setGroupId(plugin.getGroupId());

            artifacts = new SetWithResolutionResult(
                    ((ArtifactsSetWithResult) projectArtifacts).getResult(), projectArtifacts);
        } else {
            throw new IllegalArgumentException("projectArtifacts must implement ArtifactsSetWithResult");
        }

        CacheRecord record = new CacheRecord(artifacts);
        cache.put(key, record);
        return record;
    }

    @Override

    /**
     *
     * @param model the model, must not be {@code null}
     * @param logger the logger, must not be {@code null}
     */
    protected DefaultToolchain(ToolchainModel model, Logger logger) {
        this.model = model;
        this.logger = logger;
    }

    /**
     *
     * @param model the model, must not be {@code null}
     * @param type the type

     *
     * @param model The model into which to inject the default plugin executions for its packaging, must not be
     *            <code>null</code>.
     * @param request The model building request that holds further settings, must not be {@code null}.
     * @param problems The container used to collect problems that were encountered, must not be {@code null}.
     */

    private static final Map<Model, Map<List<Profile>, Model>> CACHE = Collections.synchronizedMap(new WeakHashMap<>());

    // In order for the weak hash map to work correctly, we must not hold any reference to
    // the model used as the key.  So we use a dummy model as a placeholder to indicate that
    // we want to store the model used as they key.
    private static final Model KEY = Model.newInstance();

                        false);
            }

            Parent parent = project.getModel().getDelegate().getParent();

            if (parent != null) {
                // Parent is added as an edge, but must not cause a cycle - so we remove any other edges it has
                // in conflict
                addEdge(
                        projectMap,
                        vertexMap,
                        null,