response.sendRedirect in JSP produce exception (not critical)

java.lang.IllegalStateException: Closed
at org.mortbay.jetty.HttpGenerator.prepareUncheckedAddContent(HttpGenerator.java:424)
at org.mortbay.jetty.HttpGenerator$OutputWriter.writeUtf8(HttpGenerator.java:1385)
at org.mortbay.jetty.HttpGenerator$OutputWriter.write(HttpGenerator.java:1333)
at java.io.PrintWriter.write(PrintWriter.java:382)
at org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:148)
at org.apache.jasper.runtime.PageContextImpl.release(PageContextImpl.java:216)
at org.apache.jasper.runtime.JspFactoryImpl.internalReleasePageContext(JspFactoryImpl.java:134)
at org.apache.jasper.runtime.JspFactoryImpl.releasePageContext(JspFactoryImpl.java:89)
at org.apache.jsp.admin.data.group_view_post_jsp._jspService(org.apache.jsp.admin.data.group_view_post_jsp:89)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:111)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:358)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:440)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:335)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:443)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:356)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:179)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:226)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:615)
at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:149)
at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:123)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:141)
at org.mortbay.jetty.Server.handle(Server.java:265)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:430)
at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:692)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:617)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:193)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:339)
at org.mortbay.jetty.bio.SocketConnector$Connection.run(SocketConnector.java:183)
at org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool.java:475)