}
    }

    // Test add method with null dataStore
    public void test_add_nullDataStore() {
        try {
            dataStoreFactory.add("testName", null);
            fail("Should throw IllegalArgumentException");
        } catch (IllegalArgumentException e) {
            assertEquals("name or dataStore is null.", e.getMessage());
        }
    }

    // Test add method with both null parameters

     * performing adds and removes in different ways.
     */
    runConcurrentlyMutatedTest(elements(), ops(add(1), add(2)), wrap);

    runConcurrentlyMutatedTest(elements(), ops(add(1), nop()), wrap);

    runConcurrentlyMutatedTest(elements(), ops(add(1), remove()), wrap);

    runConcurrentlyMutatedTest(elements(), ops(nop(), add(1)), wrap);

    runConcurrentlyMutatedTest(elements(1), ops(remove(), nop()), wrap);

    }

    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(

    Set<Set<Integer>> expected = new HashSet<>();
    expected.add(ImmutableSet.<Integer>of());
    expected.add(ImmutableSet.of(1));
    expected.add(ImmutableSet.of(2));
    expected.add(ImmutableSet.of(3));
    expected.add(ImmutableSet.of(1, 2));
    expected.add(ImmutableSet.of(1, 3));
    expected.add(ImmutableSet.of(2, 3));
    expected.add(ImmutableSet.of(1, 2, 3));

    add(primToWrap, wrapToPrim, boolean.class, Boolean.class);
    add(primToWrap, wrapToPrim, byte.class, Byte.class);
    add(primToWrap, wrapToPrim, char.class, Character.class);
    add(primToWrap, wrapToPrim, double.class, Double.class);
    add(primToWrap, wrapToPrim, float.class, Float.class);
    add(primToWrap, wrapToPrim, int.class, Integer.class);
    add(primToWrap, wrapToPrim, long.class, Long.class);

    testers.add(CollectionSerializationEqualTester.class);
    testers.add(MultisetAddTester.class);
    testers.add(MultisetContainsTester.class);
    testers.add(MultisetCountTester.class);
    testers.add(MultisetElementSetTester.class);
    testers.add(MultisetEqualsTester.class);
    testers.add(MultisetForEachEntryTester.class);
    testers.add(MultisetReadsTester.class);

        doc1.put("title", "Doc1");
        Map<String, Object> doc2 = new HashMap<>();
        doc2.put("title", "Doc2");
        documentList.add(doc1);
        documentList.add(doc2);
        documentList.add(doc1); // duplicate

        QueryResponseList qrList = new QueryResponseList(documentList, 0, 10, 0);

        assertEquals(0, qrList.indexOf(doc1));

	t := UTCNow()
	// Add the expiration date.
	expirationStr := fmt.Sprintf(`"expiration": "%s"`, expiration.Format(iso8601TimeFormat))
	// Add the bucket condition, only accept buckets equal to the one passed.
	bucketConditionStr := fmt.Sprintf(`["eq", "$bucket", "%s"]`, bucketName)
	// Add the key condition, only accept keys equal to the one passed.

    SetBuilderImpl<E> builder = new RegularSetBuilderImpl<>(6 + others.length);
    builder = builder.add(e1).add(e2).add(e3).add(e4).add(e5).add(e6);
    for (int i = 0; i < others.length; i++) {
      builder = builder.add(others[i]);
    }
    return builder.review().build();
  }

  /**

            ImmutableMultiset.<TypeWithDuplicates>builder().add(a).addCopies(b1, 2).add(c).build(),
            a,
            b1,
            c,
            b2);
    collector = toImmutableMultiset(e -> e, e -> 1);
    CollectorTester.of(collector, equivalence)
        .expectCollects(
            ImmutableMultiset.<TypeWithDuplicates>builder().add(a).addCopies(b1, 2).add(c).build(),
            a,
            b1,