docs: public synchronized CallableStatement prepareCall(
              String sql) throws SQLException {
  
          CallableStatement stmt;
  
          checkClosed();
  
          try {
              stmt = new JDBCCallableStatement(this, sql,
                      JDBCResultSet.TYPE_FORWARD_ONLY,
                      JDBCResultSet.CONCUR_READ_ONLY, rsHoldability);
  
              return stmt;
          } catch (HsqlException e) {
              throw Util.sqlException(e);
          }
      }