Regarding Response headers in AEM 6.3 Despatcher

We are creating generating dynamic PDF with sling servlet and flushing response with 

Content-type:application/pdf

Content-Disposition:attachment;filename=downloaded.pdf

But these values are missing in response headers and pdf got generated and flushed with the filename with the servlet name without pdf extenstion.

response headers are missing it happens only in despatcher and author environment it is working fine.

Please provide suggestions.