diff --git a/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/testdata/README.md b/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/testdata/README.md
new file mode 100644
index 00000000000..a53fe3a4a66
--- /dev/null
+++ b/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/testdata/README.md
@@ -0,0 +1,4 @@
+`swagger.json` contains static openapi definitions needed to build models for custom resource types.
+
+It was created by removing all path and non-objectmeta/int-or-string definitions from 
+the `api/openapi-spec/swagger.json` in the `k8s.io/kubernetes` module.
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