code: public static JRDesignExpression getReportConnectionExpression() {
          JRDesignExpression connectionExpression = new JRDesignExpression();
          connectionExpression.setText("$P{" + JRDesignParameter.REPORT_CONNECTION + "}");
          connectionExpression.setValueClass(Connection.class);
          return connectionExpression;
      }
docs: Returns a JRDesignExpression that points to the main report connection
  
  @return