Don't let select a paid invoice on another payment #3

/***
    @author: José Francisco Rodríguez Chávez
    @email: jfrodriguez.idempiere@gmail.com
    @created: 20/03/2018 10:45 am
    @lastupdated: 20/03/2018 10:45 am
    @version: 1.0
    @description: Don't let duplicated invoices on payment allocate
    @name: beanshell:ValidarFacturaVariosPagos
***/

import org.compiere.util.DB;
import org.compiere.util.Env;
import org.adempiere.webui.window.FDialog;

v_id_factura = A_PO.get_Value("C_Invoice_ID");

pcheck = (v_id_factura == null || v_id_factura == VOID);

if(!pcheck)
{
    String sql = "SELECT * FROM adempiere.fnt_validar_factura_varios_pagos(" + v_id_factura + ");";
    String sql2 = "SELECT * FROM adempiere.fnt_obtener_vpagos_factura(" + v_id_factura + ");";

    rows = DB.getRowSet(sql.toString());
    rows2 = DB.getRowSet(sql2.toString());

    if(rows.next())
    {
        if(rows.getBoolean(1) == false)
        {
            if(rows2.next())
            {
                String pagos = rows2.getString(1);

                return "La factura seleccionada ya esta en uso en el pago: " + pagos;
            }
        }
    }
}