SWARM-619 introduced a feature that enabled HTTP/2 by default in the HTTP/S connectors.
It works great in some environments, however this is causing some issues when deploying in Openshift, as some browsers (Chrome and Firefox) tend to upgrade the connection to HTTP/2 and present a connection error: ERROR_NET_INADEQUATE_SECURITY (with a possible workaround here) or when using Chrome returning ERR_SPDY_INADEQUATE_TRANSPORT_SECURITY (no workarounds were found so far). Apparently the lack of the ALPN library may be the cause of this issue as there may be something missing in the Openshift environment that doesn't enable HTTP/2.
WFLY-7378 verifies that and disables HTTP/2 if the requirements to use it in the enviroment are not met.
The solution I found was to comment out the line that enabled HTTP/2 by default
It should be changed to be parameterized.