I have a Action with a VistorFieldValidator for my ModelDriven object (Model.class), prior to version 2.3.20 the RequiredStringValidator looked up the message in the Model.properties file. Since 2.3.20 the validators can no longer retrieve messages from property files for the ModelDriven object. The DelegatingValidatorContext always returns the TextProvider for the Action instead of the ModelDriven object in the makeTextProvider method.
The DelegatingValidatorContext was changed in
I would submit a patch but I'm not sure of the correct behavior.
Example app with test case is here https://github.com/RLStokes/struts2-modeldriven.
The tests pass with struts 126.96.36.199 they fail with 2.3.20.