The @dataProvider annotation should be a static function, make
- ExtensionJsonTestBase::provideHookHandlerNames
- ExtensionJsonTestBase::provideContentModelIDs
- ExtensionJsonTestBase::provideApiModuleNames
- ExtensionJsonTestBase::provideApiQueryModuleListsAndNames
- ExtensionJsonTestBase::provideSpecialPageNames
- ExtensionJsonTestBase::provideAuthenticationProviders
- ExtensionJsonTestBase::provideSessionProviders
- ExtensionJsonTestBase::provideServicesLists
static and adjust the usages (More infos at T332865).
Needs some compatibility code as some other extensions sub class the abstract class.