code: public void insert(final DBObject document) {
          isTrue("already executed", !closed);
          if (document.get(ID_FIELD_NAME) == null) {
              document.put(ID_FIELD_NAME, new ObjectId());
          }
          addRequest(new InsertRequest(document, collection.getObjectCodec()));
      }
docs: Add an insert request to the bulk operation
  
  @param document the document to insert