How to add object type input argument for Blueprint

Hi, consider the following blueprint:

blueprint:
  name: Sensor - [Turn-On] Light on sensor open
  description: Turn on light on sensor open
  domain: automation
  input:
    binary_sensor:
      name: The window/door sensor that will trigger the automation
    target_light:
      name: Light
    ignore_auto_lights:
      name: Ignore the auto lights sensor (turn on always)
      default: false
    turn_on_brightness:
      name: Data to pass to the light.turn_on service
      default: None

variables: 
  ignore_auto_lights: !input ignore_auto_lights
  turn_on_brightness: !input turn_on_brightness

mode: single
condition:
  - condition: and
    conditions:
      - condition: state
        entity_id: !input target_light
        state: 'off'
      - condition: or
        conditions:
          - condition: state
            entity_id: binary_sensor.auto_lights_turn_on
            state: 'on'
          - condition: template
            value_template: "{{ ignore_auto_lights }}"
trigger:
  - platform: state
    entity_id: !input binary_sensor
    from: 'off'
    to: 'on'
action:
  - service: light.turn_on
    target:
      entity_id: !input target_light
    data: >  #here is where I don't know how to pass an object conditionally
      {{ {brightness: turn_on_brightness} }}

I would like to make my final input, turn_on_brightness be an object within the action part of the blueprint, so that I pass on Brightness, only if the brightness was configured in the automation.
I cant really find any examples anywhere in the docs on how to achieve that.