graph/users: gracefully handle PATCH requests with empty bodies

Return as success status code when the PATCH request comes with an empty
body. This is mainly to workaround issues like:
https://github.com/owncloud/web/issues/8946

services/graph/pkg/service/v0/groups.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"net/http"
 	"net/url"
+	"reflect"
 	"sort"
 	"strings"
 
@@ -130,6 +131,13 @@ func (g Graph) PatchGroup(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	if reflect.ValueOf(*changes).IsZero() {
+		logger.Debug().Interface("body", r.Body).Msg("ignoring empyt request body")
+		render.Status(r, http.StatusNoContent)
+		render.NoContent(w, r)
+		return
+	}
+
 	if changes.HasDisplayName() {
 		groupName := changes.GetDisplayName()
 		err = g.identityBackend.UpdateGroupName(r.Context(), groupID, groupName)

services/graph/pkg/service/v0/users.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"net/http"
 	"net/url"
+	"reflect"
 	"regexp"
 	"sort"
 	"strings"
@@ -646,6 +647,13 @@ func (g Graph) PatchUser(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	if reflect.ValueOf(*changes).IsZero() {
+		logger.Debug().Interface("body", r.Body).Msg("ignoring empyt request body")
+		render.Status(r, http.StatusNoContent)
+		render.NoContent(w, r)
+		return
+	}
+
 	var features []events.UserFeature
 	if mail, ok := changes.GetMailOk(); ok {
 		if !isValidEmail(*mail) {