Large POST Bodies Cause Failure with Transform Plugin

When we run traffic with small post bodies (e.g., 1024 bytes), the traffic passes through our transform plugin without issue.

When the post body is larger (e.g. 4096), the curl request fails and this message shows up in error.log "Request transformation failed to set content length".

The key difference between the working and failing case is that in the failing case, the post body is being read over multiple packets. In the working case, the post body and the request header are read together.

We first saw this in 9.1.3, but it reproduces in 10. I have a code change to make this work for me. I will post that, but I may be missing how to set the data argument for the transform.