driver-core/src/main/com/mongodb/WriteConcern.java
public boolean isAcknowledged() {
        if (w instanceof Integer) {
            return (Integer) w > 0 || (journal != null && journal) || (fsync != null && fsync);
        }
        return true;
    }
public boolean isAcknowledged() {
        if (w instanceof Integer) {
            return (Integer) w > 0 || (journal != null && journal) || (fsync != null && fsync);
        }
        return true;
    }
Returns true if this write concern indicates that write operations must be acknowledged.

@return true w != null or w &gt; 0 or journal is true or fsync is true
@mongodb.driver.manual core/write-concern/#acknowledged Acknowledged