public static String insertedIdAsString(@Nonnull InsertOneResult result) {
        return insertedId(result).toHexString();
    }
@Test
    void testInsertedIdAsString() {
        final var id = "6627add0ee216425dd6df37c";
        final var a = new DTO(id, "a");

        assertThat(insertedIdAsString(collection.insertOne(a))).isEqualTo(id);
        assertThat(insertedIdAsString(collection.insertOne(new DTO(null, "b")))).isNotBlank();
    }