code: public BulkWriteResult execute() {
          isTrue("already executed", !closed);
          closed = true;
          return collection.executeBulkWriteOperation(ordered, bypassDocumentValidation, requests);
      }
docs: Execute the bulk write operation with the default write concern of the collection from which this came.  Note that the
  continueOnError property of the write concern is ignored.
  
  @return the result of the bulk write operation.
  @throws com.mongodb.BulkWriteException if the write failed due some other failure specific to the write command
  @throws MongoException if the operation failed for some other reason