Function nm_client_checkpoint_create 

pub unsafe extern "C" fn nm_client_checkpoint_create(
    client: *mut NMClient,
    devices: *const GPtrArray,
    rollback_timeout: u32,
    flags: NMCheckpointCreateFlags,
    cancellable: *mut GCancellable,
    callback: GAsyncReadyCallback,
    user_data: gpointer,
)

Available on crate feature v1_12 only.