Can not save object correctly

[zzzgit]

class Entity{

	#id

	#content

	get id(){
		return this.#id
	}

	set id(value){
		this.#id = value
	}

	set content(value){
		this.#content = value
	}

	get content(){
		return this.#content
	}
}

This is just a simple class. I can instantiate it like this:

let entity = new Entity()

Now, I will dump it:

const yamlStr = yaml.dump(entity)
await writeToFile(thePath, yamlStr)

It just becomes an empty object in the yaml:
{}