Currently there is no constant with public static final in UndertowOptions}} to define and clarify the default value of UndertowOptions.ALLOW_UNKNOWN_PROTOCOLS.

Add that field to UndertowOptions and make sure it is used on every points where that config is read.

Also, add a javadoc that links the new field with the option it applies to with @link. And link the new constant to the Option's javadoc as well, using @link, to make both option and value fields interlinked in the documentation.