I had a tough time getting Google's batch API to process my gmail API requests using Mojolicious to generate the multipart HTTP request. Please see the batch API documentation here.
After a lot of trial and error, I figured out that I had to pad one of the requests parts, a GET request, with a blank line (\r\n) after it to get Google to process it. As far as I can tell, the RFC does not require the body in a multipart message to be followed by a new line.
I'm wondering if this is a bug and if it should be reported. I'd like to spare some people all the time I lost tracking this problem down.
Please see https://perlmonks.org/?node_id=1222593 for more details on how the HTTP request was generated.