fail bag update if the proto carries different typed attributes with same name (#4681)
fail bag update if the proto carries different typed attributes with same name (#4681)

Automatic merge from submit-queue.

fail bag update if the proto carries different typed attributes with same name

Refactor attribute update from protobuf to guard against duplicate attribute names.
Addresses TODO comment in original code
istio/pkg,istio/pkg,istio/pkg,istio/pkg,istio/pkg