@Override
    public ExchangeType exchangeType(RoutingContext routingContext) {
        // Send an aggregated response as a workaround for the following issue:
        // 1) `FallbackService` returns a response and then the only headers are written to the channel.
        // 2) The client continues to send a payload that exceeds the maximum length.
        // 3) `Http{1,2}RequestDecoder` tries to fail the request with a 413 Request Entity Too Large response.
        // 4) As the headers have already been written at 1), `fail()` resets the connection.
        // 5) A 413 status or a 404 status is expected but the client ends up with a `ClosedSessionException`.
        return ExchangeType.REQUEST_STREAMING;
    }
Handles the {@link HttpRequest}s that are not matched by any user-specified {@link Route}s.
core/src/main/java/com/linecorp/armeria/server/FallbackService.java