h.ServeHTTP(w, r)
			return
		}

		// CopyObject requests should be handled at current endpoint as path style
		// requests have target bucket and object in URI and source details are in
		// header fields
		if r.Method == http.MethodPut && r.Header.Get(xhttp.AmzCopySource) != "" {
			bucket, object = path2BucketObject(r.Header.Get(xhttp.AmzCopySource))

	"Length Required":                 http.StatusLengthRequired,
	"Precondition Failed":             http.StatusPreconditionFailed,
	"Request Entity Too Large":        http.StatusRequestEntityTooLarge,
	"Request URI Too Long":            http.StatusRequestURITooLong,
	"Unsupported Media Type":          http.StatusUnsupportedMediaType,
	"Requested Range Not Satisfiable": http.StatusRequestedRangeNotSatisfiable,

			Type:        "number",
		},
	}

	HelpMQTT = config.HelpKVS{
		config.HelpKV{
			Key:         target.MqttBroker,
			Description: "MQTT server endpoint e.g. `tcp://localhost:1883`",
			Type:        "uri",
			Sensitive:   true,
		},
		config.HelpKV{
			Key:         target.MqttTopic,
			Description: "name of the MQTT topic to publish",
			Type:        "string",
		},
		config.HelpKV{

// If input is nil an empty map is returned, not nil.
func cloneMSS(v map[string]string) map[string]string {
	r := make(map[string]string, len(v))
	for k, v := range v {
		r[k] = v
	}
	return r
}

// URI scheme constants.
const (
	httpScheme  = "http"
	httpsScheme = "https"
)

// nopCharsetConverter is a dummy charset convert which just copies input to output,