JSON in JSON field does not work

Example:

`
JSON::make("Root", [
    Text::make("Text Level 1", "level1"),
    JSON::make("Level 2", [
        Text::make("Text level 2", "text_level2")
    ], "level2")
], "json");
`

Only level1 field is added and saved in field "json". Level2 and Test_level2 are missing