import play.mvc.*;

import java.util.concurrent.CompletionStage;

public final class AnnotationAction extends play.mvc.Action.Simple {

    @Override
    public CompletionStage<Result> call(Http.Request request) {
    
            // Both of these line give a ClassCastException currently.
            // After this PR it will be a NullPointerException
            // So nothing really changes, but the exception is more accurate
            configuration.getClass();
            configuration.toString();
            
            // The only thing that changes is that after this PR we can at least check
            // for null (null = @With was used), but before this PR it was always "not null"
            if(configuration == null) {
                // @With was used - impossible to find out before
            }
            return delegate.call(request);
    }
}

    @With(AnnotationAction.class)
    public Result myAction { ... }