Any function that may create a request now has a IRequestOwner& parameter, and uses the Begin and End functions on the owner to manage the lifetime of any requests that it creates, as well as using End to invoke the completion callback for any request which has one.
The new FRequestBarrier may be used to block a group from being considered complete in a scope where more requests may be added to it.
#rb Matt.Peters
#rnx
#preflight 6109b5c403d303000144cce5
#preflight 610acf7103d30300016fda94
[CL 17060470 by Devin Doucette in ue5-main branch]
* Rename FRequest -> FZenHttpRequest to make it easier to move the implementation elsewhere
* Simplified implementation of PUT/HEAD/DELETE operations by turning template functions into plain member functions to make it easier to hide the implementation details when the class is moved into a header
#rb none
#jira none
[CL 17048397 by Stefan Boberg in ue5-main branch]
