Merges per-request transport settings over the instance-level ones.
The merge is shallow and mirrors resolveRequestOptions precedence in
RequestHandler: a field set on overrides wins; every other field keeps
the instance value. Passing no overrides returns the instance options
unchanged, so the zero-cost path stays allocation-free.
Merges per-request transport settings over the instance-level ones.
The merge is shallow and mirrors
resolveRequestOptionsprecedence inRequestHandler: a field set onoverrideswins; every other field keeps the instance value. Passing no overrides returns the instance options unchanged, so the zero-cost path stays allocation-free.