assertThrows(NullPointerException.class, () -> multimap().remove(k0(), null));
    expectUnchanged();
  }

  @MapFeature.Require(value = SUPPORTS_REMOVE, absent = ALLOWS_NULL_KEY_QUERIES)
  public void testRemoveNullKeyForbidden() {
    assertThrows(NullPointerException.class, () -> multimap().remove(null, v0()));
    expectUnchanged();
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)