Echo the server's opaque MRTR (SEP-2322) requestState back on a retried
request as the top-level params.requestState field. The client MUST NOT
inspect or modify the value, and MUST NOT include one when the server sent
none — so an empty requestState returns params unchanged.
Echo the server's opaque MRTR (SEP-2322) requestState back on a retried request as the top-level params.requestState field. The client MUST NOT inspect or modify the value, and MUST NOT include one when the server sent none — so an empty requestState returns params unchanged.