avoid concurrent reads and writes to opts.UserDefined (#14862)

do not modify opts.UserDefined after object-handler
has set all the necessary values, any mutation needed
should be done on a copy of this value not directly.

As there are other pieces of code that access opts.UserDefined
concurrently this becomes challenging.

fixes #14856

cmd/utils.go

@@ -130,6 +130,9 @@ func getWriteQuorum(drive int) int {
 	return quorum
 }
 
+// CloneMSS is an exposed function of cloneMSS for gateway usage.
+var CloneMSS = cloneMSS
+
 // cloneMSS will clone a map[string]string.
 // If input is nil an empty map is returned, not nil.
 func cloneMSS(v map[string]string) map[string]string {