Invalid format for multi-server results

The server names are not showing up here:

[domain@localhost:9999 /] /system-property=bar:add(value=foo)
{
"outcome" => "success",
"result" => {"server-groups" => [
("main-server-group" => {"master" => {
"host" => "master",
"response" =>

{"outcome" => "success"}
}}),
("other-server-group" => {"master" => {
"host" => "master",
"response" => {"outcome" => "success"}

}})
]}
}