This is a guide of sending an example exchanged token to
the jwt-authn filter and the Istio authn filter, and observing
that the example backend echoes back the request when
the authentication succeeds.

1. Open a terminal, go to the root directory of the istio-proxy repository.
Start the example backend:
    go run test/backend/echo/echo.go

2. Build the Istio proxy and run the proxy with the config for authenticating
an example exchanged token.
    bazel build //src/envoy:envoy
    bazel-bin/src/envoy/envoy -l debug -c src/envoy/http/authn/sample/APToken/aptoken-envoy.conf

3. Open a terminal, go to the root directory of the istio-proxy repository.
Send a request with the example exchanged token.
    export token=$(cat src/envoy/http/authn/sample/APToken/APToken-example1.jwt)
    curl --header "ingress-authorization:$token" http://localhost:9090/echo -d "hello world"
