code: static TableReference getTableReference(Configuration conf) throws IOException {
      // Ensure the BigQuery output information is valid.
      String projectId = getProjectId(conf);
      String datasetId =
          ConfigurationUtil.getMandatoryConfig(conf, BigQueryConfiguration.OUTPUT_DATASET_ID_KEY);
      String tableId =
          ConfigurationUtil.getMandatoryConfig(conf, BigQueryConfiguration.OUTPUT_TABLE_ID_KEY);
  
      return new TableReference().setProjectId(projectId).setDatasetId(datasetId).setTableId(tableId);
    }
docs: Gets the output table reference based on the given configuration. If the {@link
  BigQueryConfiguration#OUTPUT_PROJECT_ID_KEY} is missing, this resolves to referencing the
  {@link BigQueryConfiguration#PROJECT_ID_KEY} key.
  
  @param conf the configuration to reference the keys from.
  @return a reference to the derived output table in the format of "<project>:<dataset>.<table>".
  @throws IOException if a required key is missing.