code: public Table updateTableExpiration(String datasetName, String tableName) {
      // [START bigquery_update_table_expiration]
      Table beforeTable = bigquery.getTable(datasetName, tableName);
  
      // Set table to expire 5 days from now.
      long expirationMillis = Instant.now().plus(5, ChronoUnit.DAYS).toEpochMilli();
      TableInfo tableInfo = beforeTable.toBuilder().setExpirationTime(expirationMillis).build();
      Table afterTable = bigquery.update(tableInfo);
      // [END bigquery_update_table_expiration]
      return afterTable;
    }
docs: [VARIABLE "my_table_name"]