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());

            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);
    }

    /**

        if (opLambda != null) {
            opLambda.callback(builder);
        }
    }

    public void setId_NotEqual(String id) {
        setId_NotTerm(id, null);
    }

    public void setId_NotTerm(String id) {
        setId_NotTerm(id, null);
    }

    public void setId_NotEqual(String id, ConditionOptionCall<BoolQueryBuilder> opLambda) {

        SearchLogCQ cq = new SearchLogCQ();
        if (queryLambda != null) {
            queryLambda.callback(cq);
        }
        FilterAggregationBuilder builder = regFilterA(name, cq.getQuery());
        if (opLambda != null) {
            opLambda.callback(builder);
        }
        if (aggsLambda != null) {
            SearchLogCA ca = new SearchLogCA();
            aggsLambda.callback(ca);

      return;
    }

    map.put(null, unmappedValue);
    assertEquals(unmappedValue, map.get(null));
    assertTrue(map.containsKey(null));
    Entry<@Nullable K, V> entry = mapEntry(null, unmappedValue);
    assertTrue(entrySet.remove(entry));
    assertNull(map.get(null));
    assertFalse(map.containsKey(null));
  }

  public void testEntrySetRemoveNullKeyMissing() {

            return null;
        }
        synchronized (this.addressCache) {
            CacheEntry entry = this.addressCache.get(hostName);
            if (entry != null && entry.expiration < System.currentTimeMillis() && entry.expiration >= 0) {
                entry = null;
            }
            return entry != null ? entry.address : null;
        }
    }

    int getNextNameTrnId() {

     * 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;
    }

        if (opLambda != null) {
            opLambda.callback(builder);
        }
    }

    public void setId_NotEqual(String id) {
        setId_NotTerm(id, null);
    }

    public void setId_NotTerm(String id) {
        setId_NotTerm(id, null);
    }

    public void setId_NotEqual(String id, ConditionOptionCall<BoolQueryBuilder> opLambda) {

     *
     * @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.