cl-rest-config.json gets overwritten using Docker Image

[timmornYE]

Using the Docker Image provided at https://hub.docker.com/r/saubyk/c-lightning-rest cl-rest-config.json always gets overwritten by the default

{
"PORT": 3001,
"DOCPORT": 4001,
"PROTOCOL": "https",
"EXECMODE": "production",
"RPCCOMMANDS": ""
}

every time I start the container. Tried to make an own image where I keep care that my config is there from beginning. But no matter what I do... it always gets replaced by default. I do not think this is desired behaviour?