collector.add(Problem.Severity.ERROR, "Error message", 10, 5, null);
        collector.add(Problem.Severity.WARNING, "Warning message", 15, 3, null);

        List<Problem> problems = collector.getProblems();
        assertEquals(2, problems.size(), "Should collect both problems");
        assertEquals(Problem.Severity.ERROR, problems.get(0).getSeverity(), "First problem should be ERROR");

     */
    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}.
     */

                        location = problem.getSource();
                    }
                    if (problem.getLineNumber() > 0) {
                        if (!location.isEmpty()) {
                            location += ", ";
                        }
                        location += "line " + problem.getLineNumber();
                    }

/**
 * 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 {

    /**

     * @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()) {

        DefaultProblemCollector collector = new DefaultProblemCollector(null);

        collector.add(null, "PROBLEM1", -1, -1, null);

        collector.setSource("SOURCE_PROBLEM2");
        collector.add(null, "PROBLEM2", -1, -1, null);

        collector.setSource("SOURCE_PROBLEM3");
        collector.add(null, "PROBLEM3", -1, -1, null);

        assertEquals("", collector.getProblems().get(0).getSource());

     * @param problems the collection of problems to include in the message
     * @return a formatted message including details of all problems
     */
    protected static String buildMessage(String message, ProblemCollector<BuilderProblem> problems) {
        StringBuilder msg = new StringBuilder(message);
        problems.problems().forEach(problem -> msg.append("\n * ")
                .append(problem.getSeverity().name())

     * @param line The one-based index of the line containing the problem or {@code -1} if unknown.
     * @param column The one-based index of the column containing the problem or {@code -1} if unknown.
     * @param cause The cause of the problem, may be {@code null}.
     */
    void add(SettingsProblem.Severity severity, String message, int line, int column, Exception cause);

        assertEquals(
                "1 problem was encountered while building the effective toolchains" + LS
                        + "[ERROR] MESSAGE @ line 3, column 5" + LS,
                e.getMessage());
    }

    @Test
    void testUnknownPositionAndSource() {
        ProblemCollector problemCollector = ProblemCollectorFactory.newInstance(null);
        problemCollector.add(Problem.Severity.ERROR, "MESSAGE", -1, -1, new Exception());

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 {

    /**