public JavadocOptionFileOptionInternal<List<List<String>>> duplicate() {
        List<List<String>> copyValues = new ArrayList<>();
        for (List<String> occurrence : getValue()) {
            copyValues.add(Lists.newArrayList(occurrence));
        }
        return new MultilineMultiValueJavadocOptionFileOption(option, copyValues, joinBy);
    }

    @Override

		"j": {"1", "2"},
		"m": nil,
	}
	for i := 0; i < b.N; i++ {
		dst := url.Values{"a": {"b"}, "b": {"2"}, "c": {"3"}, "d": {"4"}, "j": nil, "m": {"x"}}
		copyValues(dst, src)
		if valuesCount = len(dst["a"]); valuesCount != 6 {
			b.Fatalf(`%d items in dst["a"] but expected 6`, valuesCount)
		}
	}
	if valuesCount == 0 {
		b.Fatal("Benchmark wasn't run")
	}
}