Abstraction ECDS config discovery header file to make it extendable (#20445)
Abstraction ECDS config discovery header file to make it extendable (#20445)

* Further abstraction ECDS config discovery header file to make it extendable to other filters.

Signed-off-by: Yanjun Xiang <e47001e055dffa8c99dcb68ae3a77f0b4a730805@google.com>
envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy,envoyproxy/envoy