Rename PrefixedRedirect to FlushingHandler & comment

It's not clear whether this code is necessary, but investigating
this was outside of the scope of this PR.

server/mux.go

@@ -321,9 +321,9 @@ func NewMux(opts MuxOpts, service Service) http.Handler {
 
 		// Create middleware that redirects to the appropriate provider logout
 		router.GET("/oauth/logout", Logout("/", opts.Basepath, allRoutes.AuthRoutes))
-		out = Logger(opts.Logger, PrefixedRedirect(auth))
+		out = Logger(opts.Logger, FlushingHandler(auth))
 	} else {
-		out = Logger(opts.Logger, PrefixedRedirect(router))
+		out = Logger(opts.Logger, FlushingHandler(router))
 	}
 
 	return out

server/prefixing_redirector.go

@@ -4,28 +4,29 @@ import (
 	"net/http"
 )
 
-type interceptingResponseWriter struct {
+type flushingResponseWriter struct {
 	http.ResponseWriter
 }
 
-func (i *interceptingResponseWriter) WriteHeader(status int) {
-	i.ResponseWriter.WriteHeader(status)
+func (f *flushingResponseWriter) WriteHeader(status int) {
+	f.ResponseWriter.WriteHeader(status)
 }
 
 // Flush is here because the underlying HTTP chunked transfer response writer
 // to implement http.Flusher.  Without it data is silently buffered.  This
 // was discovered when proxying kapacitor chunked logs.
-func (i *interceptingResponseWriter) Flush() {
-	if flusher, ok := i.ResponseWriter.(http.Flusher); ok {
+func (f *flushingResponseWriter) Flush() {
+	if flusher, ok := f.ResponseWriter.(http.Flusher); ok {
 		flusher.Flush()
 	}
 }
 
-// PrefixedRedirect alters the Location header of downstream http.Handlers
-// to include a specified prefix
-func PrefixedRedirect(next http.Handler) http.Handler {
+// FlushingHandler may not actually do anything, but it was ostensibly
+// implemented to flush response writers that can be flushed for the
+// purposes in the comment above.
+func FlushingHandler(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		iw := &interceptingResponseWriter{
+		iw := &flushingResponseWriter{
 			ResponseWriter: w,
 		}
 		next.ServeHTTP(iw, r)