Господа!
Подскажите пожалуйста, в чем причина такого exception?
Используется JSF и JasperReports.
На страничке имеется линк

  <h:commandLink action="#{myBean.showReport}" actionListener="#{myBean.putParameters}">
                        <h:outputText value="Report" />
 </h:commandLink>

В myBean

  public String showReport()
    {
        if (reportName == null)
        {
            return null;
        }

        prepareReport();
        FacesContext facesContext = FacesContext.getCurrentInstance();
        ExternalContext externalContext = facesContext.getExternalContext();
        HttpServletRequest servletRequest = (HttpServletRequest) externalContext.getRequest();
        if (servletRequest != null)
        {
            servletRequest.setAttribute("nameInSession", reportName);
        }
        return "showReport";
    }

В faces-config.xml

<navigation-rule>
        <from-view-id>*</from-view-id>
        <navigation-case>
            <from-outcome>showReport</from-outcome>
            <to-view-id>/report</to-view-id>
        </navigation-case>
    </navigation-rule>

В web.xml

   <servlet>
        <servlet-name>ReportServlet</servlet-name>
        <servlet-class>my.servlets.ReportServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>ReportServlet</servlet-name>
        <url-pattern>/report</url-pattern>
    </servlet-mapping>

В ReportServlet

  private void showReport(ReportProvider reportProvider, HttpServletResponse response, String nameForStore) throws IOException
  {
      byte[] reportContentInBytes = myBean.getBytes();
      String format = myBean.getFormat();
      String ext = null;
      if (format.equalsIgnoreCase("application/pdf"))
      {
          ext = ".pdf";
      }
     

      if (reportContentInBytes != null && nameForStore != null && ext != null)
      {
          response.setContentType("application/x-download");
          response.setContentLength(reportContentInBytes.length);
          response.setHeader("Content-Disposition", "attachment; filename=" + nameForStore + ext);
          OutputStream outputStream = response.getOutputStream();
          outputStream.write(reportContentInBytes, 0, reportContentInBytes.length);
          outputStream.flush();
          outputStream.close();
      }
  }

В месте OutputStream outputStream = response.getOutputStream(); выпадает exception

ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[localhost].[/cm84].[FacesServlet]] Servlet.service() for servlet FacesServlet threw exception
java.lang.IllegalStateException
    at com.sun.faces.application.ViewHandlerResponseWrapper.getOutputStream(ViewHandlerResponseWrapper.java:179)
    at my.servlets.ReportServlet.showReport(ReportServlet.java:86)
    at my.servlets.ReportServlet.service(ReportServlet.java:43)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

Где искать причину?