*/
    Exception getException();

    /**
     * Gets the message that describes this problem.
     *
     * @return The message describing this problem, never {@code null}.
     */
    String getMessage();

    /**
     * Gets the severity level of this problem.
     *
     * @return The severity level of this problem, never {@code null}.
     */

        problem = new DefaultProblem(null, null, "", -1, -1, null);
        assertEquals("", problem.getSource());

        problem = new DefaultProblem(null, null, "SOURCE", -1, -1, null);
        assertEquals("SOURCE", problem.getSource());
    }

    @Test
    void testGetLocation() {
        DefaultProblem problem = new DefaultProblem(null, null, null, -1, -1, null);
        assertEquals("", problem.getLocation());

     */
    Exception getException();

    /**
     * Gets the message that describes this problem.
     *
     * @return The message describing this problem, never {@code null}.
     */
    String getMessage();

    /**
     * Gets the severity level of this problem.
     *
     * @return The severity level of this problem, never {@code null}.
     */

/**
 * Describes a problem that was encountered during project 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.
 *
 * @since 4.0.0
 */
@Experimental
@Immutable
public interface BuilderProblem {

    /**

    }

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

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

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

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

    @Override

    }

    @Override
    public List<Problem> getProblems() {
        return problems;
    }

    @Override
    public void setSource(String source) {
        this.source = source;
    }

    @Override
    public void add(Problem.Severity severity, String message, int line, int column, Exception cause) {
        Problem problem = new DefaultProblem(message, severity, source, line, column, cause);

package org.apache.maven.api.services;

import org.apache.maven.api.annotations.Nonnull;

/**
 * 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.
 *
 */
public interface ModelProblem extends BuilderProblem {

    /**

    /**
     * Reports a problem: always maintains the counters, but whether problem is preserved in memory, depends on
     * implementation and its configuration.
     *
     * @param problem the problem to report
     * @return {@code true} if passed problem is preserved by this call.
     */
    boolean reportProblem(P problem);

    /**

     */
    Exception getException();

    /**
     * Gets the message that describes this problem.
     *
     * @return The message describing this problem, never {@code null}.
     */
    String getMessage();

    /**
     * Gets the severity level of this problem.
     *
     * @return The severity level of this problem, never {@code null}.
     */

Here's what to keep in mind and how to review a pull request:

### Understand the problem { #understand-the-problem }

* First, make sure you **understand the problem** that the pull request is trying to solve. It might have a longer discussion in a GitHub Discussion or issue.

* There's also a good chance that the pull request is not actually needed because the problem can be solved in a **different way**. Then you can suggest or ask about that.