title: Response already committed error happening
body: <p>I'm trying to use Servlet to download data as CSV, and as the JSP is included with <code>flush=true</code>. The stack trace is provided below. The report is getting saved as expected but I can see an exception in the back. Can you please help me figure out why? I have closed the <code>OutputStream</code> and also tried flushing the buffer, but still no luck.       </p>
  
  <pre><code>1:36:38,304 ERROR [[jsp]] Servlet.service() for servlet jsp threw exception
  java.lang.IllegalStateException: getOutputStream() has already been called for this response
      at org.apache.catalina.connector.Response.getWriter(Response.java:619)
      at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:198)
      at org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:125)
      at org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:118)
      at org.apache.jasper.runtime.JspWriterImpl.flush(JspWriterImpl.java:173)
      at atg.taglib.dspjsp.IncludeTag.flushOut(IncludeTag.java:873)
      at atg.taglib.dspjsp.IncludeTag.doEndTag(IncludeTag.java:773)
  </code></pre>
  
  <hr>
  
  <pre><code>pResponse.setContentType(MS_EXCEL);
  pResponse.setHeader(CONTENT,FILENAME);
  
  outputStream = pResponse.getOutputStream();
  pResponse.flushBuffer();
  workbook.write(outputStream);
  outputStream.flush();
  outputStream.close();
  </code></pre>