Getting started: https://dzone.com/refcardz/getting-started-apache-wicket Wicket official docs: https://ci.apache.org/projects/wicket/guide/7.x/guide/single.html

Migration references:

• Migrate from 1.4 to 1.5
• Migrate from 1.5 to 6.0
• Migrate from 6.0 to 7.0

Old branch migrating a 2013 GeoServer towards 6.0 and full diff against its baseline

Justin's previous page Wicket-UI-TODOs on this subject.

Who's working on what https://docs.google.com/spreadsheets/d/1yzE9W4ZaIUcmE1XRcHCTih2mLEhMhVoZxKQl_k1n7D8/edit?ts=569d2137#gid=0

• ResourceReference -> PackageResourceReference
• ParamResourceModel -> StringResourceModel (the Wicket 7 class is fluent enough that we don't need ParamResourceModel anymore)
• PageParameters -> has been moved in a different pakage, the way to fill it is different
• AjaxRequestTarget.addComponent --> AjaxRequestTarget.add
• SimpleAttributeModifier --> AttributeModifier.replace

• Add all missing generics
• Check internationalization (in particular, that params are properly passed down into messages, as a bonus, find a way to check for i18n keys that are no more in use).
• Check that WicketCallback changes did not break the callbacks (some are pretty important)
• Check that the PageParameters migration picked the right to<TargetType> vs toOptional<TargetType> form
• AbstractValidator is no more there, see the guide on how to implement from interface
• Component visit has changed, see this bit of the Wicket 1.5 migration guide for reference
• IAjaxCallDecorator -> IAjaxCallListener, see the Ajax guide for details
• HeaderContributor has gone. See https://cwiki.apache.org/confluence/display/WICKET/Migration+to+Wicket+1.5#MigrationtoWicket1.5-RemovedHeaderContributorandfriends.

Some ideas for making use of Java 8 features when updating wicket code.

Lambda expressions can be automagically for interfaces that have one "abstract" method (ie @FunctionalInterface). This replaces the use of anonymous classes in many wicket examples.

Use of lambda to replace IVisitor:

visitChildren((Component c, final IVisit<Void> visit) -> {
   c.setEnabled(enabled);
});