Problema ao fazer um método para download usando Jboss seam

import javax.faces.context.ExternalContext;

import javax.faces.context.FacesContext;

import javax.persistence.EntityManager;

import javax.servlet.ServletOutputStream;

import javax.servlet.http.HttpServletResponse;

import org.domain.crudimagem.entity.Arquivo;

import org.jboss.seam.annotations.In;

import org.jboss.seam.annotations.Name;

import org.jboss.seam.annotations.web.RequestParameter;

@In
private EntityManager entityManager;

@In(value="#{facesContext.externalContext}")
private ExternalContext extCtx;

@In(value="#{facesContext}")
FacesContext facesContext;

@RequestParameter
private Integer arquivoId;

public String download(){
	
	Arquivo arquivo = entityManager.find(Arquivo.class, arquivoId); 
	
	HttpServletResponse response = (HttpServletResponse) extCtx.getResponse();
	
	response.setContentType(arquivo.getContentType());
	
	response.addHeader("Content-disposition", "arquivo; filename=\"" + arquivo.getDescricao() +"\"");
	
	try{
		ServletOutputStream os = response.getOutputStream();
		os.write(arquivo.getData());
		os.flush();
		os.close();
		facesContext.responseComplete();
	}catch(Exception e){
		e.printStackTrace();
	}
	
	return null;
}

java.lang.IllegalStateException: Servlet response already use stream, Writer not possible

at org.ajax4jsf.webapp.FilterServletResponseWrapper.getWriter(FilterServletResponseWrapper.java:207)

at javax.servlet.ServletResponseWrapper.getWriter(ServletResponseWrapper.java:112)

at com.sun.facelets.FaceletViewHandler.createResponseWriter(FaceletViewHandler.java:414)

at com.sun.facelets.FaceletViewHandler.renderView(FaceletViewHandler.java:571)

at org.ajax4jsf.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:100)

at org.ajax4jsf.application.AjaxViewHandler.renderView(AjaxViewHandler.java:176)

at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:110)

at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)

at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)

at javax.faces.webapp.FacesServlet.service(FacesServlet.java:266)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:83)

at org.jboss.seam.web.IdentityFilter.doFilter(IdentityFilter.java:40)

at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)

at org.jboss.seam.web.MultipartFilter.doFilter(MultipartFilter.java:90)

at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)

at org.jboss.seam.web.ExceptionFilter.doFilter(ExceptionFilter.java:64)

at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)

at org.jboss.seam.web.RedirectFilter.doFilter(RedirectFilter.java:45)

at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)

at org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:178)

at org.ajax4jsf.webapp.BaseFilter.handleRequest(BaseFilter.java:290)

at org.ajax4jsf.webapp.BaseFilter.processUploadsAndHandleRequest(BaseFilter.java:390)

at org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:517)

at org.jboss.seam.web.Ajax4jsfFilter.doFilter(Ajax4jsfFilter.java:56)

at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)

at org.jboss.seam.web.LoggingFilter.doFilter(LoggingFilter.java:60)

at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)

at org.jboss.seam.web.HotDeployFilter.doFilter(HotDeployFilter.java:53)

at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)

at org.jboss.seam.servlet.SeamFilter.doFilter(SeamFilter.java:158)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:235)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)

at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:190)

at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:433)

at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:92)

at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.process(SecurityContextEstablishmentValve.java:126)

at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:70)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)

at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:330)

at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:829)

at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:601)

at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)

at java.lang.Thread.run(Thread.java:619)