the Hydrator ClassMethods has a property only accesible though __construct underscoreSeparatedKeys, but there is no way to define this value though Form notation, or change it later on in the controller though any setter due the HydratorInterface doesn't has it defined.

Suggestion1: Change the Hydrator notation from AbstractStringAnnotation to AbstractArrayAnnotation and be something like this: @Zend\Form\Annotation\Hydrator({"class":"Zend\Stdlib\Hydrator\ClassMethods", "underscoreSeparatedKeys":false}) The rest of the Hydrators can happily ignore such additional params, and in ClassMethods if not defined can use default just as is right now.

Actually I ugly patched putting default to false instead of true to make this work with my Anotation definitions.