Replace it with standard Java 8 java.util.function.Supplier<T> which is virtually identical.
Replace IContextProvider<T, C> with standard Java 8 java.util.function.Function<C, T> which is virtually identical.
As a consequence IPageManagerProvider, IPageRendererProvider and IRequestCycleProvider now override #apply() method instead of #get().
Tests based on HtmlDocumentValidator are very fragile. They start to fail as soon as there is a single character change somewhere in the page markup.
We believe that there are very few users of this API. It is recommended to use TagTester and WicketTestCase#executeTest() instead.
Use an anonymous instance of IModel instead. Since Wicket 8.0 IModel doesn't require providing implementation of #setObject(Object) method.
IGenericComponent's setter methods now return the current instance for method chaining
All specialization classes return their type.
AjaxSubmitLink and AjaxFallbackButton event callback methods no longer get form as second argument
server ASF JIRA serverId 5aa69414-a9e9-3523-82ec-879b028fb15b key WICKET-6184
For consistency with other components and the new lambda support, the submitted form is no longer passed as argument to callback methods (e.g. #onSubmit(), #onClick()) of AjaxButton, AjaxLink AjaxSubmitLink and AjaxFallbackButton. You can call #getForm() instead.