The upgrade to 4.0.0 includes rendering changes that ensure ad rendering in your app matches the previews shown in the AdSense preview. For text ads these differences are minimal, but for product ads they may be more pronounced. Please check all your styles before release and contact your account manager if necessary to resolve rendering issues.
The GANSearchAdController's populateAdView method now can take an optional callback that will let your app know when the AdView is ready to be displayed. This callback also provides the height of the adview if that is needed for rendering.
All previusly marked deprecated methods, classes, and enums have been removed.
The prefetchEnabled field in GANSearchAdControllerOptions has been removed.