}

  @CollectionFeature.Require({SUPPORTS_REMOVE, ALLOWS_NULL_VALUES})
  @CollectionSize.Require(ONE)
  public void testRetainAll_nullSingletonPreviouslySingletonWithNull() {
    initCollectionWithNullElement();
    expectReturnsFalse(nullSingleton);
    expectContents(createArrayWithNullElement());
  }

  @CollectionFeature.Require({SUPPORTS_REMOVE, ALLOWS_NULL_VALUES})
  @CollectionSize.Require(absent = {ZERO, ONE})

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require({SUPPORTS_REMOVE, ALLOWS_NULL_VALUES})
  public void testSetCount_removeNull_nullSupported() {
    initCollectionWithNullElement();
    assertSetCount(null, 0);
  }

  @CollectionFeature.Require(
      value = {SUPPORTS_ADD, ALLOWS_NULL_VALUES},
      absent = RESTRICTS_ELEMENTS)
  public void testSetCount_addNull_nullSupported() {

            .withFeatures(CollectionSize.ANY, CollectionFeature.ALLOWS_NULL_VALUES)
            .named("Multisets.union")
            .createTestSuite());

    suite.addTest(
        MultisetTestSuiteBuilder.using(intersectionGenerator())
            .withFeatures(
                CollectionSize.ANY,
                CollectionFeature.ALLOWS_NULL_VALUES,
                CollectionFeature.KNOWN_ORDER)

import static com.google.common.collect.testing.features.MapFeature.ALLOWS_NULL_KEY_QUERIES;
import static com.google.common.collect.testing.features.MapFeature.ALLOWS_NULL_VALUES;
import static com.google.common.collect.testing.features.MapFeature.ALLOWS_NULL_VALUE_QUERIES;
import static com.google.common.collect.testing.google.ReflectionFreeAssertThrows.assertThrows;

                    return union(emptySet(), emptySet());
                  }
                })
            .named("empty U empty")
            .withFeatures(CollectionSize.ZERO, CollectionFeature.ALLOWS_NULL_VALUES)
            .createTestSuite());

    suite.addTest(
        SetTestSuiteBuilder.using(
                new TestStringSetGenerator() {
                  @Override

 * limitations under the License.
 */

package com.google.common.collect.testing.testers;

import static com.google.common.collect.testing.features.CollectionFeature.ALLOWS_NULL_VALUES;
import static com.google.common.collect.testing.features.CollectionFeature.KNOWN_ORDER;
import static com.google.common.collect.testing.features.CollectionFeature.SUPPORTS_ADD;

  }

  @MapFeature.Require(value = SUPPORTS_PUT, absent = ALLOWS_NULL_VALUES)
  @CollectionSize.Require(absent = ZERO)
  public void testSetValueNullUnsupported() {
    for (Entry<K, V> entry : getMap().entrySet()) {
      assertThrows(NullPointerException.class, () -> entry.setValue(null));
      expectUnchanged();
    }
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_VALUES})
  @CollectionSize.Require(absent = ZERO)

  @CollectionFeature.Require(ALLOWS_NULL_VALUES)
  @CollectionSize.Require(absent = ZERO)
  public void testCreateWithNull_supported() {
    E[] array = createArrayWithNullElement();
    collection = getSubjectGenerator().create(array);
    expectContents(array);
  }

  @CollectionFeature.Require(absent = ALLOWS_NULL_VALUES)
  @CollectionSize.Require(absent = ZERO)

import static com.google.common.collect.testing.Helpers.getMethod;
import static com.google.common.collect.testing.features.CollectionFeature.ALLOWS_NULL_QUERIES;
import static com.google.common.collect.testing.features.CollectionFeature.ALLOWS_NULL_VALUES;
import static com.google.common.collect.testing.features.CollectionSize.SEVERAL;
import static com.google.common.collect.testing.features.CollectionSize.ZERO;

  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_VALUES})
  public void testPut_nullValueSupported() {
    assertNull("put(key, null) should return null", put(nullValueEntry));
    expectAdded(nullValueEntry);
  }

  @MapFeature.Require(value = SUPPORTS_PUT, absent = ALLOWS_NULL_VALUES)
  public void testPut_nullValueUnsupported() {