// 3. Exploiting the power of arrays

MongoCollection<Document> collection = client

  .getDatabase("test")

  .getCollection("arrayUpdatesTest");

collection.updateOne(

  Filters.eq("_id", 1),

  Updates.set("a.$[i].b", 2),

new UpdateOptions()

  .arrayFilters(

    Collections.singletonList(

      Filters.eq("i.b", 0))));