feat: support baggage propagation in httpc (#2375)

* feat: support baggage propagation in httpc

* chore: use go 1.16

* chore: use go 1.16

* chore: use go ^1.16

* chore: remove deprecated

rest/handler/loghandler_test.go

@@ -3,7 +3,6 @@ package handler
 import (
 	"bytes"
 	"io"
-	"io/ioutil"
 	"log"
 	"net/http"
 	"net/http/httptest"
@@ -15,7 +14,7 @@ import (
 )
 
 func init() {
-	log.SetOutput(ioutil.Discard)
+	log.SetOutput(io.Discard)
 }
 
 func TestLogHandler(t *testing.T) {
@@ -55,7 +54,7 @@ func TestLogHandlerVeryLong(t *testing.T) {
 	req := httptest.NewRequest(http.MethodPost, "http://localhost", &buf)
 	handler := LogHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		r.Context().Value(internal.LogContext).(*internal.LogCollector).Append("anything")
-		io.Copy(ioutil.Discard, r.Body)
+		io.Copy(io.Discard, r.Body)
 		w.Header().Set("X-Test", "test")
 		w.WriteHeader(http.StatusServiceUnavailable)
 		_, err := w.Write([]byte("content"))