code: @Override
      public MongoDeepJobConfig<T> inputColumns(String... columns) {
          DBObject bsonFields = fields != null ? fields : new BasicDBObject();
          boolean isIdPresent = false;
          for (String column : columns) {
              if (column.trim().equalsIgnoreCase("_id")) {
                  isIdPresent = true;
              }
  
              bsonFields.put(column.trim(), 1);
          }
          if (!isIdPresent) {
              bsonFields.put("_id", 0);
          }
          fields = bsonFields;
          return this;
      }
docs: {@inheritDoc}