def METHOD_NAME(
    coresys: CoreSys, addonsdata_system: dict[str, Data], os_environ
):
    """Validate defaults for mapped folders in addons."""
    docker_addon = get_docker_addon(
        coresys, addonsdata_system, "basic-addon-config.json"
    )
    # Config added and is marked rw
    assert (
        Mount(
            type="bind",
            source=coresys.config.path_extern_homeassistant.as_posix(),
            target="/config",
            read_only=False,
        )
        in docker_addon.mounts
    )
    # SSL added and defaults to ro
    assert (
        Mount(
            type="bind",
            source=coresys.config.path_extern_ssl.as_posix(),
            target="/ssl",
            read_only=True,
        )
        in docker_addon.mounts
    )
    # Media added and propagation set
    assert (
        Mount(
            type="bind",
            source=coresys.config.path_extern_media.as_posix(),
            target="/media",
            read_only=True,
            propagation="rslave",
        )
        in docker_addon.mounts
    )
    # Share added and propagation set
    assert (
        Mount(
            type="bind",
            source=coresys.config.path_extern_share.as_posix(),
            target="/share",
            read_only=True,
            propagation="rslave",
        )
        in docker_addon.mounts
    )
    # Backup not added
    assert "/backup" not in [mount["Target"] for mount in docker_addon.mounts]