private List<Problem> problems;

    /**
     * Default constructor
     *
     * @param effectiveToolchains the merged toolchains, may not be {@code null}
     * @param problems the problems while building the effectiveToolchains, if any.
     */
    public DefaultToolchainsBuildingResult(PersistedToolchains effectiveToolchains, List<Problem> problems) {
        this.effectiveToolchains = effectiveToolchains;

 */
package org.apache.maven.model.building;

import org.apache.maven.model.Model;

/**
 * Describes a problem that was encountered during model 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 POM file that exhibits
 * the problem.
 *
 * @deprecated use {@link org.apache.maven.api.services.ModelBuilder} instead
 */

                }

                private BuilderProblem toProblem(ModelProblem problem) {
                    return new BuilderProblem() {
                        @Override
                        public String getSource() {
                            return problem.getSource();
                        }

                        @Override

     *
     * @return The assembled toolchains, never {@code null}.
     */
    PersistedToolchains getEffectiveToolchains();

    /**
     * Return a list of problems, if any.
     *
     * @return a list of problems, never {@code null}.
     */
    List<Problem> getProblems();

            writer.print(modelId);
        }

        for (ModelProblem problem : problems) {
            writer.println();
            writer.print("    - [");
            writer.print(problem.getSeverity());
            writer.print("] ");
            writer.print(problem.getMessage());
            String location = ModelProblemUtils.formatLocation(problem, modelId);
            if (!location.isEmpty()) {

                if (!modelResult.getProblems().isEmpty()) {
                    List<ModelProblem> problems = modelResult.getProblems();
                    if (logger.isDebugEnabled()) {
                        String problem = (problems.size() == 1) ? "problem" : "problems";
                        String problemPredicate = problem + ((problems.size() == 1) ? " was" : " were");
                        String message = String.format(

### Suggest solutions

* After being able to understand the question, you can give them a possible **answer**.

* In many cases, it's better to understand their **underlying problem or use case**, because there might be a better way to solve it than what they are trying to do.

            };
        } else {
            return null;
        }
    }

    private List<Problem> convert(List<BuilderProblem> problems) {
        ProblemCollector collector = ProblemCollectorFactory.newInstance(null);
        problems.forEach(p -> collector.add(
                Problem.Severity.valueOf(p.getSeverity().name()),
                p.getMessage(),
                p.getLineNumber(),

        writer.print(problems.size());
        writer.print((problems.size() == 1) ? " problem was " : " problems were ");
        writer.print("encountered while building the effective settings");
        writer.println();

        for (SettingsProblem problem : problems) {
            writer.print("[");
            writer.print(problem.getSeverity());
            writer.print("] ");
            writer.print(problem.getMessage());

 * providing a simple error message, leaving the donkey work of creating a nice model problem to this component.
 *
 * @deprecated use {@link org.apache.maven.api.services.ModelBuilder} instead
 */
@Deprecated(since = "4.0.0")
public interface ModelProblemCollector {

    /**
     * Adds the specified problem.
     *
     * @param req must not be null
     */