Use WriteConcern in MongoCollection.deleteMany in mongo-java-driver 3.12

I am using mongo-java-driver-3.12.X version. I want to change the deprecated API

DBCollection.remove(query, WriteConcern.UNACKNOWLEDGED);

to

MongoCollection.deleteMany(query)

1. Is there a way to specify WriteConcern?
2. What will be the default behaviour if WriteConcern is not specified?

You can easily find this information in the driver documentation.

WriteConcern can be set to multiple level for 3.12 version it goes like this.

MongoClient:

MongoClientOptions options = MongoClientOptions.builder().writeConcern(WriteConcern.UNACKNOWLEDGED).build();
MongoClient mongoClient = new MongoClient(Arrays.asList(
        new ServerAddress("host1", 27017),
        new ServerAddress("host1", 27018)), options);

or with a connection string

MongoClient mongoClient = new MongoClient(new MongoClientURI("mongodb://host1:27017,host2:27017/?w=unacknowledged"));

MongoDatabase

MongoDatabase database = mongoClient.getDatabase("test").withWriteConcern(WriteConcern.UNACKNOWLEDGED);

MongoCollection

This is the case you are interested in

MongoCollection<Document> collection = database.getCollection("restaurants").withWriteConcern(WriteConcern.UNACKNOWLEDGED);
collection.deleteMany(query);

Keep in mind that MongoCollection and MongoDatabase are immutable so calling withWriteConcern create a new instance and has no effect on the original instance.

For the default behavior you need to check the documentation because it depends on your mongodb version.