Apache httpd since 2.4.44 support since the proxy check_trans hook that allows a better processing of the websocket upgrades. If your httpd is older use the patch: http://people.apache.org/~covener/patches/wstunnel-decline.diff
Simple example use:
ProxyPass "/" "ws://localhost:8080/"
ProxyPass "/" "http://localhost:8080/"
ProxyPassReverse "/" "http://localhost:8080/"
Change WSUpgradeHeader none to WSUpgradeHeader ANY and use JBCS httpd-2.4.37 SP6
Note that httpd-trunk needs WSUpgradeHeader "*" instead ANY
See https://issues.redhat.com/browse/JBCS-291 and https://issues.redhat.com/browse/MODCLUSTER-580