Update-codegen.sh get a wrong package name

[huangzixun123]

1. git clone https://github.com/kubernetes/sample-controller
2. modify the sample-controller to cnat-client-go
3. modify pkg/apis/samplecontroller to pkg/apis/samplecontroller
4. modify the hack/update-codegen.sh as following

set -o errexit
set -o nounset
set -o pipefail

SCRIPT_ROOT=$(dirname "${BASH_SOURCE[0]}")/..
CODEGEN_PKG=${CODEGEN_PKG:-$(cd "${SCRIPT_ROOT}"; ls -d -1 ./vendor/k8s.io/code-generator 2>/dev/null || echo ../code-generator)}

# generate the code with:
# --output-base    because this script should also be able to run inside the vendor dir of
#                  k8s.io/kubernetes. The output-base is needed for the generators to output into the vendor dir
#                  instead of the $GOPATH directly. For normal projects this can be dropped.
"${CODEGEN_PKG}"/generate-groups.sh "deepcopy,client,informer,lister" \
  github.com/programming-kubernetes/cnat/cnat-client-go/pkg/generated github.com/programming-kubernetes/cnat/cnat-client-go/pkg/apis \
  cnat:v1alpha1 \
  --output-base "$(dirname "${BASH_SOURCE[0]}")/../../../../.." \
  --go-header-file "${SCRIPT_ROOT}"/hack/boilerplate.go.txt

6. exec the codegen script

./hack/update-codegen.sh 

but i get a wrong package name, like this,
samplecontrollerv1alpha1 "k8s.io/sample-controller/pkg/apis/cnat/samplecontroller/v1alpha1
could anyone tell me how i can fix this?