[1.20.1] create JSON file with using ForgeConfigSpec

[pobab]

im trying store some data that generated from WSS(WebSocketSecure) into JSON file

Forge MDK have common TOML config with using ForgeConfigSpec. in otherside, i wanna create JSON file with using ForgeConfigSpec. i take a look into External Libraries, Forge had use com.electronwill.night-config:toml:3.6.4  & com.electronwill.night-config:core:3.6.4 and unfortunately... i think ForgeConfigSpec only support TOML. but i've been implement com.electronwill.night-config:json:3.6.7 and now i dont have idea how to write ForgeConfigSpec as JSON file, does anyone know about that? please help me figure out how to write it

[pobab]

this is what i've been do since i think ForgeConfigSpec can't handle JSON file

@SubscribeEvent
static void onLoad(final ModConfigEvent event) {
    LOGGER.info(PREFIX);
    LOGGER.info(PREFIX+"Generating config");
    FileConfig config = FileConfig.of(CONFIG_FILE);
    config.set("pobab", "5000");
    config.save();
    config.close();
    LOGGER.info(PREFIX+"successful generated");
    LOGGER.info(PREFIX);
}

but, it said

[07:44:51] [main/ERROR] [ne.mi.fm.ja.FMLModContainer/]: Exception caught during firing event: No suitable format for forgeria-data.json

here is the full log