I've tried to upload a 28 MB large app and the request failed with:
java.io.IOException: UT000020: Connection terminated as request was larger than 10485760

What's worse, the response isn't JSON so the UI got an exception and got stuck.

REQUEST:
POST /rhamt-web/api/migrationProjects/1675/registeredApplications/upload HTTP/1.1
Host: localhost:8080
Connection: keep-alive
Content-Length: 29028737
Referer: http://localhost:8080/rhamt-web/projects/1675/applications/register
...

HTTP/1.1 400 Bad Request
Expires: 0
Cache-Control: no-cache, no-store, must-revalidate
X-Powered-By: Undertow/1
Server: WildFly/10
Pragma: no-cache
Date: Tue, 08 Aug 2017 07:42:53 GMT
Connection: close
Content-Type: text/html
Content-Length: 88

java.io.IOException: UT000020: Connection terminated as request was larger than 10485760