}

    default void add(BuilderProblem.Severity severity, ModelProblem.Version version, String message) {
        add(severity, version, message, null, null);
    }

    default void add(
            BuilderProblem.Severity severity, ModelProblem.Version version, String message, InputLocation location) {
        add(severity, version, message, location, null);
    }

    default void add(

    String getMessage();

    /**
     * Gets the severity level of this problem.
     *
     * @return the severity level of this problem, never {@code null}
     */
    @Nonnull
    Severity getSeverity();

    /**
     * The different severity levels for a problem, in decreasing order.
     *
     * @since 4.0.0
     */
    @Experimental
    enum Severity {
        FATAL, //
        ERROR, //

        collector.setSource("pom.xml");
        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");

        collector.add(null, "MESSAGE1", -1, -1, null);

        Exception e2 = new Exception();
        collector.add(Severity.WARNING, null, 42, 127, e2);

        assertEquals(2, collector.getProblems().size());

        Problem p1 = collector.getProblems().get(0);
        assertEquals(Severity.ERROR, p1.getSeverity());
        assertEquals("MESSAGE1", p1.getMessage());
        assertEquals(-1, p1.getLineNumber());

    }

    @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);

        problems.add(problem);
    }

        }
        canceled -> {
          events += "plan $id TCP connect canceled"
          ConnectResult(this, nextPlan = connectTcpNextPlan, throwable = IOException("canceled"))
        }
        connectTcpNextPlan != null -> {
          events += "plan $id needs follow-up"
          ConnectResult(this, nextPlan = connectTcpNextPlan)
        }
        else -> {
          events += "plan $id TCP connected"

  }

  fun assertExhausted() {
    assertThat(events).isEmpty()
  }

  fun assertOpen(): WebSocket {
    val event = nextEvent() as Open
    return event.webSocket
  }

  fun assertFailure(t: Throwable?) {
    val event = nextEvent() as Failure
    assertThat(event.response).isNull()
    assertThat(event.t).isSameAs(t)
  }

  fun assertFailure(

 */
@Deprecated(since = "4.0.0")
public interface ProblemCollector {

    /**
     * Adds the specified problem.
     * Either message or exception is required
     *
     * @param severity The severity of the problem, must not be {@code null}.
     * @param message The detail message of the problem, may be {@code null}.
     * @param line The one-based index of the line containing the problem or {@code -1} if unknown.

    @Nonnull
    Settings getEffectiveSettings();

    /**
     * Gets the problems that were encountered during the settings building. Note that only problems of severity
     * {@link BuilderProblem.Severity#WARNING} and below are reported here. Problems with a higher severity level cause
     * the settings builder to fail with a {@link SettingsBuilderException}.
     *

    PersistedToolchains getEffectiveToolchains();

    /**
     * Gets the problems that were encountered during the settings building. Note that only problems of severity
     * {@link BuilderProblem.Severity#WARNING} and below are reported here. Problems with a higher severity level cause
     * the settings builder to fail with a {@link ToolchainsBuilderException}.
     *