StringBuilder sb = new StringBuilder("Append StringBulder demo: ");
joined = Joiner.on(", ").skipNulls().appendTo(sb, fantasyGenres).toString();
assertThat(joined).isEqualTo("Append StringBulder demo: Space Opera, Horror, Magic realism, Religion");
// reuse joiner
Joiner joiner = Joiner.on(", ");
joiner.join(fantasyGenres);
joiner.join(fantasyGenres2);
}