In configuration guide in the chapter A.22. Undertow Subsystem Attributes, there is a section called Server Attributes, which holds following list:

• server
  • http-listener
  • https-listener
  • ajp-listener
  • host
    • access-log (part of settings)
    • single-sign-on (part of settings)
    • filter-ref
    • location
      • filter-ref

Each of these is a link to particular sub-section table. host link in this case is broken and links to the host attribute table of the reverse-proxy handler. I believe it is caused simply by that these two (at least) share the very same 'anchor id' which is used as a link. Therefore it is neccessary to make those ids unique, I think.