Http-equiv="refresh" is not used + web page is not displayed

I’m trying to see if I can put Inception behind Shinyproxy by adding the following configuration to the application.yml file.

Inception provides at startup a html file which uses <meta http-equiv="refresh" content="5"/> to refresh the content every 5 seconds untill the Spring Java webapp is up and running.

<!DOCTYPE html>

  <meta charset="utf-8"/>
  <meta http-equiv="refresh" content="5"/>

  <title>INCEpTION - Starting up...</title>


  <div class="page-content flex-h-container">
    <div class="scrolling flex-content flex-h-container flex-centered">
      <div class="flex-content flex-v-container flex-centered">
        <h1>INCEpTION is starting up...</h1>
        <p style="text-align: center;">
          This page will automatically refresh itself every 5 seconds until the application is running. Please wait.
  <div class="page-footer">
      <span class=text-muted> Technische Universität Darmstadt -- Computer Science Department -- INCEpTION </span>


When running this behind ShinyProxy, the shown application stays at that webpage, meaning the http-equiv=“refresh” never triggers the refreshing of the webpage. It also does not display the html of it.

While if I go into the running container and perform a wget to the URL, I see that the webpage is no longer at startup.html but it has already changed.
Why does Shinyproxy does not use this meta http-equiv=“refresh” content=“5”? Is there a Shinyproxy setting which I can use to make sure the refresh is done?

docker exec -it jolly_mcnulty bash

root@158519bbe281:/opt/inception# wget localhost:8080
--2023-10-19 12:40:30--  http://localhost:8080/
Resolving localhost (localhost)..., ::1
Connecting to localhost (localhost)||:8080... connected.
HTTP request sent, awaiting response... 302 
Location: http://localhost:8080/login.html [following]
--2023-10-19 12:40:30--  http://localhost:8080/login.html
Reusing existing connection to localhost:8080.
HTTP request sent, awaiting response... 200 
Length: unspecified [text/html]
Saving to: ‘index.html’

index.html                                           [ <=>                                                                                                      ]   7.50K  --.-KB/s    in 0.001s  

2023-10-19 12:40:41 (8.06 MB/s) - ‘index.html’ saved [7682]     

root@158519bbe281:/opt/inception# cat index.html
<!DOCTYPE html>

<meta charset=utf-8>
<meta http-equiv=X-UA-Compatible content="IE=edge">
<meta name=viewport content="width=device-width, initial-scale=1">
<meta name=google content=notranslate>
<link rel="icon" href="favicon.png" type="image/x-icon"/>
<title>INCEpTION - Log in </title>
<script type="text/javascript" src="./wicket/resource/org.apache.wicket.resource.JQueryResourceReference/jquery/jquery-3.6.4-ver-A66F0A69D13CAE7E761635A40954CBF9.js" nonce="P5-v5NYQm_lf146-vm5Ue_oz"></script>
<script type="text/javascript" id="popover" nonce="P5-v5NYQm_lf146-vm5Ue_oz">
$(function () {