In the configuration guide, CHAPTER 17. CONFIGURING THE WEB SERVER (UNDERTOW), section 17.5. CONFIGURING HANDLERS, there is a paragraph with following content:

File handlers serve static files. Each file handler must be attached to a location in a virtual host. Reverse-proxy handlers allow JBoss EAP to serve as a high performance reverse-proxy. It can handle AJP, HTTP, and HTTP.2 back ends and supports mod_cluster.

I am not comfortable with the last sentence much. It states HTTP and HTTP.2 separately. This is confusing - why is there no protocol version in the HTTP, also latter one should be written rather as HTTP/2. Also mod_cluster can be configured as separate filter in Undertow's subsystem. To mention it here seems a little bit confusing to me.

Lets just remove that last sentence, so paragraph would go like:

File handlers serve static files. Each file handler must be attached to a location in a virtual host. Reverse-proxy handlers allow JBoss EAP to serve as a high performance reverse-proxy.