assertThrows(NullPointerException.class, () -> multimap().put(k1(), null));

    expectUnchanged();
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_KEYS})
  public void testPutNullKey() {
    int size = getNumElements();

    multimap().put(null, v3());

    assertGet(null, v3());
    assertEquals(size + 1, multimap().size());
  }

  @MapFeature.Require(SUPPORTS_PUT)

    assertThrows(NullPointerException.class, () -> multimap().put(k1(), null));

    expectUnchanged();
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_KEYS})
  public void testPutNullKey() {
    int size = getNumElements();

    multimap().put(null, v3());

    assertGet(null, v3());
    assertEquals(size + 1, multimap().size());
  }

  @MapFeature.Require(SUPPORTS_PUT)

      assertEquals(initialSize, map.size());
    } else {
      assertThrows(UnsupportedOperationException.class, () -> map.put(keyToPut, valueToPut));
    }
    assertInvariants(map);
  }

  public void testPutNullKey() {
    if (!supportsPut) {
      return;
    }
    Map<K, V> map = makeEitherMap();
    V valueToPut;
    try {
      valueToPut = getValueNotInPopulatedMap();

      assertEquals(initialSize, map.size());
    } else {
      assertThrows(UnsupportedOperationException.class, () -> map.put(keyToPut, valueToPut));
    }
    assertInvariants(map);
  }

  public void testPutNullKey() {
    if (!supportsPut) {
      return;
    }
    Map<K, V> map = makeEitherMap();
    V valueToPut;
    try {
      valueToPut = getValueNotInPopulatedMap();