how to provide namespace wtih grpcurl

Hi All,
I am using grpcurl to get list of images from containerd as follows:

grpcurl -plaintext -proto images.proto -unix /run/containerd/containerd.sock containerd.services.images.v1.Images/List

but getting following error:
ERROR:
Code: FailedPrecondition
Message: namespace is required: failed precondition

I tried giving the namespace as follows , but then getting another error:
./grpcurl -plaintext -d '{"namespace":"k8s.io"}' -proto images.proto -unix /run/containerd/containerd.sock containerd.services.images.v1.Images/List
Error invoking method "containerd.services.images.v1.Images/List": error getting request data: message type containerd.services.images.v1.ListImagesRequest has no known field named namespace

How can I give the namespace with grpcurl ?

Thanks