code: protected CustomDriverStatement getCustomDriverStatement(String[] sqlTokens) {
      if (sqlTokens.length > 0) {
        for (CustomDriverStatement statement : customDriverStatements) {
          if (sqlTokens[0].equalsIgnoreCase(statement.statement)) {
            return statement;
          }
        }
      }
      return null;
    }
docs: Checks if a sql statement is a custom statement only recognized by this driver
  
  @param sqlTokens The statement to check
  @return The custom driver statement if the given statement is a custom statement only
  recognized by the Cloud Spanner JDBC driver, such as show_ddl_operations