Thank you, Mark,
Although now I found the solution also. As your solution suggest I need to remove the pdf extension from request Uri and I also need to change the base Uri to the Api request Uri, (as the one shown in image is not Api request Uri) After that I was able to get the bytes [] successfully. Accept Header I used for all my request has always been set to application/pdf
Thank you for your help.
Regards,
Rashpal