Need help figuring out how to use `ExtProcPerRoute` to disable external processing filter for specific routes

[Filip]

Hi,

Reading up on ExtProcPerRoute and I wanted to give it a try but unfortunately I wasn't able to figure out how I could use it in either a static configuration (envoy.yaml) or dynamic one (xds grpc server). 

Can anyone help me out with some documentation references, integration tests or code examples? I've tried the java control plane for the xds server but any other language implementation will do just fine.

Thank you,

/Filip

[Ross Morrow]

I agree. Following the example of the ExternalAuth filter, I have this trivial example (for local testing) working to disable/enable a set ExtProc filters: 
```
route_config:
  name: local_route
  virtual_hosts:
    - name: local_service
      domains: ["*"]
      routes:
        - match:
            prefix: "/"
            headers:
              - name: "x-use-extproc-filters"
                present_match: true
          route:
            cluster: echo
        - match:
            prefix: "/"
          route:
            cluster: echo
          typed_per_filter_config:
            envoy.filters.http.ext_proc:
              "@type": type.googleapis.com/envoy.extensions.filters.http.ext_proc.v3.ExtProcPerRoute
              disabled: true
```