expression {
  const_expr {
    int64_value: 13
  }
}
request_headers {
  headers{key: ":method" value : "GET"}
  headers{key: ":path" value : "/"}
  headers{key: ":scheme" value : "http"}
  headers{key: ":authority" value : "foo.com"}
  headers {}
  headers {}
  headers {}
  headers {}
  headers {}
}
response_headers {
  headers {
    key: ":status"
    value : "200"
  }
}
trailers {
  headers {}
}
stream_info {}