code: @Deprecated
      public DBObject unlock() {
          return DBObjects.toDBObject(createOperationExecutor().execute(new FsyncUnlockOperation(), readPreference, readConcern));
      }
docs: Unlocks the database, allowing the write operations to go through. This command may be asynchronous on the server, which means there
  may be a small delay before the database becomes writable.
  
  @return {@code DBObject} in the following form {@code {"ok": 1,"info": "unlock completed"}}
  @throws MongoException if there's a failure
  @mongodb.driver.manual reference/command/fsync/ fsync command