Fix downcasting to v0.3 from v1.0 (#272)
Fix downcasting to v0.3 from v1.0 (#272)

* fixing v1 codec

Signed-off-by: nachocano <cfa30924d66f50abad7358bae51eb7ca86d4fc8b@google.com>

cloudevents/sdk-go,cloudevents/sdk-go