Groups: Add GetTransitiveMembers

This PR extends the project to include transitive listing of group members as `msgraph.User`.
The addition of this method should not be confused with `ListTransitiveMembers` as it returns a `*[]string`, which forces the user to first list, and then get each individual member by ID.

More information about the `transitiveMembers` endpoint can be found [here](https://learn.microsoft.com/en-us/graph/api/group-list-transitivemembers?view=graph-rest-1.0&tabs=http)

msgraph/groups.go

@@ -358,6 +358,41 @@ func (c *GroupsClient) ListMembers(ctx context.Context, id string) (*[]string, i
 	return &ret, status, nil
 }
 
+// GetTransitiveMembers retrieves all nested members of the specified Group.
+// id is the object ID of the group.
+func (c *GroupsClient) GetTransitiveMembers(ctx context.Context, groupId string, query odata.Query) (*[]User, int, error) {
+	query.Expand = odata.Expand{Relationship: "*"}
+
+	resp, status, _, err := c.BaseClient.Get(ctx, GetHttpRequestInput{
+		ConsistencyFailureFunc: RetryOn404ConsistencyFailureFunc,
+		OData:                  query,
+		ValidStatusCodes:       []int{http.StatusOK},
+		Uri: Uri{
+			Entity: fmt.Sprintf("/groups/%s/transitiveMembers", groupId),
+		},
+	})
+
+	if err != nil {
+		return nil, status, fmt.Errorf("GroupsClient.BaseClient.Get(): %v", err)
+	}
+
+	defer resp.Body.Close()
+	respBody, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, status, fmt.Errorf("io.ReadAll(): %v", err)
+	}
+
+	var data struct {
+		Users []User `json:"value"`
+	}
+
+	if err = json.Unmarshal(respBody, &data); err != nil {
+		return nil, status, fmt.Errorf("json.Unmarshal(): %v", err)
+	}
+
+	return &data.Users, status, nil
+}
+
 // ListTransitiveMembers retrieves a flat list of all nested members of the specified Group.
 // id is the object ID of the group.
 func (c *GroupsClient) ListTransitiveMembers(ctx context.Context, id string) (*[]string, int, error) {

msgraph/groups_test.go

@@ -39,9 +39,11 @@ func TestGroupsClient(t *testing.T) {
 	testGroupsClient_GetOwner(t, c, *group.ID(), (*owners)[0])
 
 	members := testGroupsClient_ListMembers(t, c, *group.ID())
-	transitiveMembers := testGroupsClient_ListTransitiveMembers(t, c, *group.ID())
+	listedTransitiveMembers := testGroupsClient_ListTransitiveMembers(t, c, *group.ID())
+	transitiveMembers := testGroupsClient_GetTransitiveMembers(t, c, *group.ID())
 	testGroupsClient_GetMember(t, c, *group.ID(), (*members)[0])
-	testGroupsClient_GetMember(t, c, *group.ID(), (*transitiveMembers)[0])
+	testGroupsClient_GetMember(t, c, *group.ID(), (*listedTransitiveMembers)[0])
+	testGroupsClient_GetMember(t, c, *group.ID(), *(*transitiveMembers)[0].ID())
 	testGroupsClient_GetMembers(t, c, *group.ID(), odata.Query{})
 
 	group.DisplayName = utils.StringPtr(fmt.Sprintf("test-updated-group-%s", c.RandomString))
@@ -242,6 +244,23 @@ func testGroupsClient_ListMembers(t *testing.T, c *test.Test, id string) (member
 	return
 }
 
+func testGroupsClient_GetTransitiveMembers(t *testing.T, c *test.Test, id string) (members *[]msgraph.User) {
+	members, status, err := c.GroupsClient.GetTransitiveMembers(c.Context, id, odata.Query{})
+	if err != nil {
+		t.Fatalf("GroupsClient.GetTransitiveMembers(): %v", err)
+	}
+	if status != 200 {
+		t.Fatalf("GroupsClient.GetTransitiveMembers(): invalid status: %d", status)
+	}
+	if members == nil {
+		t.Fatal("GroupsClient.GetTransitiveMembers(): members was nil")
+	}
+	if len(*members) == 0 {
+		t.Fatal("GroupsClient.GetTransitiveMembers(): members was empty")
+	}
+	return
+}
+
 func testGroupsClient_ListTransitiveMembers(t *testing.T, c *test.Test, id string) (members *[]string) {
 	members, status, err := c.GroupsClient.ListTransitiveMembers(c.Context, id)
 	if err != nil {