I have good news! I solved the trouble changing http undertow configuration. I had read-timeout and write-timeout with 30s configured. When I removed this parameters, the warnings disappear. Let me show how my configuration is:
Before:
<http-listener name="default" socket-binding="http" redirect-socket="https" enable-http2="true" read-timeout="30000" write-time-out="30000" />
After:
<http-listener name="default" socket-binding="http" redirect-socket="https" enable-http2="true" />