update decoder to use GroupVersion

pkg/runtime/codec.go

@@ -35,6 +35,7 @@ type yamlCodec struct {
 
 // yamlCodec implements Codec
 var _ Codec = yamlCodec{}
+var _ Decoder = yamlCodec{}
 
 // YAMLDecoder adds YAML decoding support to a codec that supports JSON.
 func YAMLDecoder(codec Codec) Codec {
@@ -75,6 +76,8 @@ type codecWrapper struct {
 	version string
 }
 
+var _ Decoder = &codecWrapper{}
+
 // Encode implements Codec
 func (c *codecWrapper) Encode(obj Object) ([]byte, error) {
 	return c.EncodeToVersion(obj, c.version)