MQTT discovery question (min_mireds, max_mireds)

Hello, guys! I’m developing a rather simple MQTT LED driver based on ESP8266 with brightness / color temperature adjustment. Everything is fine, but I have a question about MQTT discovery. I want to send min_mireds and max_mireds values from my driver to hassio, but hassio refuses to accept them. Here is the code and it’s working fine.

  staticJsonDocument_led1["name"] = "ESP8266 Nr. 1, LED Nr. 1";
  staticJsonDocument_led1["platform"] = "mqtt";
  staticJsonDocument_led1["schema"] = "json";
  staticJsonDocument_led1["command_topic"] = "homeassistant/light/esp8266-1/led-1/command";
  staticJsonDocument_led1["state_topic"] = "homeassistant/light/esp8266-1/led-1/state";
  staticJsonDocument_led1["brightness"] = "true";
  staticJsonDocument_led1["color_temp"] = "true";

But if I add the following it stops working.

  staticJsonDocument_led1["min_mireds"] = 170; //sample value
  staticJsonDocument_led1["max_mireds"] = 320; //sample value

What am I doing wrong? Thanks!