throw new CrawlerSystemException(
                    "URL pattern regular expression is null or blank. Cannot register client without a valid pattern.");
        }
        if (client == null) {
            throw new CrawlerSystemException("CrawlerClient instance is null. Cannot register null client.");
        }
        clientMap.put(Pattern.compile(regex), client);
    }

    /**

    protected final ColumnInfo _columnSortOrder = cci("sortOrder", "sortOrder", null, null, Integer.class, "sortOrder", null, false, false,
            false, "Integer", 0, 0, null, null, false, null, null, null, null, null, false);
    protected final ColumnInfo _columnTarget = cci("target", "target", null, null, String.class, "target", null, false, false, false,

     * If the provided UrlQueueService is null, it removes the current instance from the thread-local variable.
     *
     * @param urlQueueService the UrlQueueService instance to be set, or null to remove the current instance
     */
    public static void setUrlQueueService(final UrlQueueService<UrlQueue<?>> urlQueueService) {
        if (urlQueueService == null) {
            URL_QUEUE_SERVICE_THREAD_LOCAL.remove();

        int result = 1;
        result = prime * result + ((value1 == null) ? 0 : value1.hashCode());
        result = prime * result + ((value2 == null) ? 0 : value2.hashCode());
        result = prime * result + ((value3 == null) ? 0 : value3.hashCode());
        result = prime * result + ((value4 == null) ? 0 : value4.hashCode());
        result = prime * result + ((value5 == null) ? 0 : value5.hashCode());
        return result;
    }

    void equalsAndHashCode_subjectSemantics() {
        Kerb5Authenticator a = new Kerb5Authenticator((Subject) null);
        Kerb5Authenticator b = new Kerb5Authenticator((Subject) null);

        // Both null subjects -> equal
        assertEquals(a, b);
        assertEquals(a.hashCode(), b.hashCode());

        // Mixed null/non-null -> not equal
        Kerb5Authenticator c = new Kerb5Authenticator(new Subject());

        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());

        }
    }

    private Result<ProjectDependencyGraph> sessionDependencyGraph(final MavenSession session)
            throws CycleDetectedException, DuplicateProjectException {
        Result<ProjectDependencyGraph> result = null;

        if (session.getProjectDependencyGraph() != null || session.getProjects() != null) {

     *
     * @param message The message describing the problem, may be {@code null}.
     * @param severity The severity level of the problem, may be {@code null} to default to
     *            {@link ModelProblem.Severity#ERROR}.
     * @param source The source of the problem, may be {@code null}.
     * @param lineNumber The one-based index of the line containing the error or {@code -1} if unknown.

    internal var request: Request? = null
    internal var protocol: Protocol? = null
    internal var code = -1
    internal var message: String? = null
    internal var handshake: Handshake? = null
    internal var headers: Headers.Builder
    internal var body: ResponseBody = ResponseBody.EMPTY
    internal var socket: Socket? = null
    internal var networkResponse: Response? = null

    checkFromStringCase("google.com:-25", 1, null, 99, false);
    checkFromStringCase("google.com:+25", 1, null, 99, false);
    checkFromStringCase("google.com:25  ", 1, null, 99, false);
    checkFromStringCase("google.com:25\t", 1, null, 99, false);
    checkFromStringCase("google.com:0x25 ", 1, null, 99, false);
  }

  public void testFromStringUnparseableNonsense() {