}

  @MapFeature.Require(SUPPORTS_PUT)
  // Empty multimaps *do* have defined equals semantics.
  @SuppressWarnings("UndefinedEquals")
  public void testPutAllIntoEmpty() {
    Multimap<K, V> target = getSubjectGenerator().create();
    assertEquals(!multimap().isEmpty(), target.putAll(multimap()));
    assertEquals(multimap(), target);
  }

  @MapFeature.Require(SUPPORTS_PUT)