Currently there is no constant with public static final in UndertowOptions}} to define and clarify the default value of UndertowOptions.HTTP2_SETTINGS_INITIAL_WINDOW_SIZE.

Verify if that config has a default value inside Undertow. If so, add that field to UndertowOptions and make sure it is used on every points where that config is read.

Also, if you created the constant, 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.

Otherwise, state clearly in the Javadoc that this option has no default value.