code: @Override
  	public void flushBuffer() throws IOException {
  
  		//PrintWriter.flush() does not throw exception
  		if (this.printWriter != null) {
  			this.printWriter.flush();
  		}
  
  		if (this.gzipOutputStream != null) {
  			this.gzipOutputStream.flush();
  		}
  
  		// doing this might leads to response already committed exception
  		// when the PageInfo has not yet built but the buffer already flushed
  		// Happens in Weblogic when a servlet forward to a JSP page and the forward
  		// method trigger a flush before it forwarded to the JSP
  		// disableFlushBuffer for that purpose is 'true' by default
  		if (!disableFlushBuffer) {
  			super.flushBuffer();
  		}
  	}
docs: Flush OutputStream or PrintWriter.
  
  @throws IOException ex