import java.util.ArrayList;
import java.util.List;

/**
 * Collects problems that are encountered during settings building.
 *
 */
class DefaultProblemCollector implements ProblemCollector {

    private final List<Problem> problems;

    private String source;

    DefaultProblemCollector(List<Problem> problems) {
        this.problems = (problems != null) ? problems : new ArrayList<>();
    }

    @Override

                                problem.getLineNumber() > 0 ? "line " + problem.getLineNumber() : "",
                                problem.getColumnNumber() > 0 ? "column " + problem.getColumnNumber() : "")
                        .filter(s -> !s.isEmpty())
                        .collect(Collectors.joining(", "));
                if (!loc.isEmpty()) {

        private final SettingsProblem problem;

        MappedBuilderProblem(SettingsProblem problem) {
            this.problem = problem;
        }

        @Override
        public String getSource() {
            return problem.getSource();
        }

        @Override
        public int getLineNumber() {
            return problem.getLineNumber();
        }

        @Override

 * providing a simple error message, leaving the donkey work of creating a nice model problem to this component.
 *
 */
public interface ModelProblemCollector {

    /**
     * The collected problems.
     * @return a list of model problems encountered, never {@code null}
     */
    List<ModelProblem> getProblems();

    boolean hasErrors();

 */
package org.apache.maven.building;

/**
 * Describes a problem that was encountered during settings building. A problem can either be an exception that was
 * thrown or a simple string message. In addition, a problem carries a hint about its source, e.g. the settings file
 * that exhibits the problem.
 *
 */
class DefaultProblem implements Problem {

    private final String source;

    private final int lineNumber;

                    return defaultModelBuilder.readRawModel(req, problems);
                } catch (ModelBuilderException e) {
                    // gathered with problem collector
                }
                return null;
            }
        };
    }

    private boolean addEdge(Path from, Path p, DefaultModelProblemCollector problems) {
        try {
            dag.addEdge(from.toString(), p.toString());

        if (hasErrors(problems)) {
            throw new ToolchainsBuilderException("Error building toolchains", problems);
        }

        return new DefaultToolchainsBuilderResult(effective, problems);
    }

    private boolean hasErrors(List<BuilderProblem> problems) {
        if (problems != null) {
            for (BuilderProblem problem : problems) {

    }

    @Override
    public void add(ModelProblem problem) {
        problems.add(problem);

        severities.add(problem.getSeverity());
    }

    public void addAll(Collection<ModelProblem> problems) {
        this.problems.addAll(problems);

        for (ModelProblem problem : problems) {
            severities.add(problem.getSeverity());
        }
    }

    @Override

     * @return The formatted problem location or an empty string if unknown, never {@code null}.
     */
    public static String formatLocation(ModelProblem problem, String projectId) {
        StringBuilder buffer = new StringBuilder(256);

        if (!problem.getModelId().equals(projectId)) {
            buffer.append(problem.getModelId());
            if (!problem.getSource().isEmpty()) {

/**
 * Exception which occurs to indicate that the plugin cannot be initialized due
 * to some deeper problem with Plexus. Context information includes the groupId,
 * artifactId, and version for the plugin; at times, the goal name for which
 * execution failed; a message detailing the problem; the ClassRealm used to
 * look up the plugin; and the Plexus exception that caused this error.
 *
 *
 */