Allow interop client to use call creds on any secure channel (#2185)
Allow interop client to use call creds on any secure channel (#2185)


thinkerou/grpc-go,menghanl/grpc-go,improbable-io/grpc-go,thinkerou/grpc-go,dfawley/grpc-go,grpc/grpc-go,improbable-io/grpc-go,stanley-cheung/grpc-go,stanley-cheung/grpc-go,dfawley/grpc-go,grpc/grpc-go,menghanl/grpc-go