[jboss-as7-dev] Do new model attributes require manual setup of transformers?

I've been trying to implement a new feature which requires the addition of a new model attribute for the EJB3 subsystem root resource. This model attribute is supposed to be "mandatory" (i.e. non-nullable at model level and "required" at xml level). All works fine without bringing into picture older versions of the model. Now while testing with older versions of the model and compatibility, things start failing for obvious reasons- the older model handlers, parsers etc... have no clue about this new attribute. I'm aware that that's where the transformers come into picture and I've setup an appropriate transformer that is supposed to handle this scenario. But, the transformers tests in EJB3SubsystemUnitTestCase fails for different test methods. I had to dig a bit into the code to figure out that one of the failures had to do with the test case itself rather than the new code. One part of the problem and the main reason why I decided to ask this via a mail instead of over IRC is because, I've been having a difficult time with the transformer APIs and its usage. On a higher level I (think) I do understand what the transformers are supposed to do and how to deal with individual attribute/resource changes when multiple versions of the model come into picture. But when it comes to wiring the right transformers at the right place in the code or figuring out what such places are or even debugging failing tests, I find it not so straightforward to understand what's going on. Perhaps it's just that I am not yet used to those APIs. To be honest, with whatever transformer code I've added, although it seems to work to a certain extent, I'm not confident about the code I'm adding - I've been just looking at other places and copying over the code wherever appropriate. So back to the original issue and the related question - would it be possible to "automate" this process of plugging in these transformers? In this specific case, for example, I think almost all (there maybe be exceptions) subsystems and resources introducing a new attribute in the higher model would expect that that attribute to be ignored (I'm not using the term discarded or rejected because I am not 100% sure I understand the difference yet :) ) by lower versions of the model. So instead of me trying to figure out where to plugin these transformers, would it be possible to *dynamically* generate these transformers for some of these cases? That way I wouldn't have to deal with these for every new attribute and instead be assured that this would be handled centrally at some place? P.S: If someone wants to take a look at the (failing WIP) code that I'm talking about, then let me know, I can push my code to github. I wanted to keep this mail to be broader than just this specific failing case. -Jaikiran