How to add new endpoint to Guacamole application?

Question

I've found this repositry: https://github.com/ridvanaltun/guacamole-rest-api-documentation/tree/master

There are listed existing endpoints of guacamole.

Also I was able to run docker compose takens from here:

version: '2.0'

# networks
# create a network 'guacnetwork_compose' in mode 'bridged'
networks:
  guacnetwork_compose:
    driver: bridge

# services
services:
  # guacd
  guacd:
    container_name: guacd_compose
    image: guacamole/guacd
    networks:
      guacnetwork_compose:
    restart: always
    volumes:
    - ./drive:/drive:rw
    - ./record:/record:rw
  # postgres
  postgres:
    container_name: postgres_guacamole_compose
    environment:
      PGDATA: /var/lib/postgresql/data/guacamole
      POSTGRES_DB: guacamole_db
      POSTGRES_PASSWORD: 'ChooseYourOwnPasswordHere1234'
      POSTGRES_USER: guacamole_user
    image: postgres:15.2-alpine
    networks:
      guacnetwork_compose:
    restart: always
    volumes:
    - ./init:/docker-entrypoint-initdb.d:z
    - ./data:/var/lib/postgresql/data:Z

  # guacamole
  guacamole:
    container_name: guacamole_compose
    depends_on:
    - guacd
    - postgres
    environment:
      GUACD_HOSTNAME: guacd
      POSTGRES_DATABASE: guacamole_db
      POSTGRES_HOSTNAME: postgres
      POSTGRES_PASSWORD: 'ChooseYourOwnPasswordHere1234'
      POSTGRES_USER: guacamole_user
    image: guacamole/guacamole
    links:
    - guacd
    networks:
      guacnetwork_compose:
    ports:
## enable next line if not using nginx
    - 8080:8080/tcp # Guacamole is on :8080/guacamole, not /.
    restart: always

Now I want to add new endpoint which will return some information from postgres database. What it the correct way to do it ?