I think this is a bug, but I'm not entirely sure as it may just be unclear from the spec.
When I define a @BeanParam and specify jaxrs annotations on the private fields with a no-arg constructor, everything seems to work as expected, but when I define a @BeanParam using jaxrs annotations on the ctor params, I get an error during initialization stating that a no-arg constructor is expected. Since you can use jaxrs annotations on constructor args for resource classes, i'd assume the same for beanparam classes.
Thoughts?
P.S. I was unable to assign this discussion to the RestEasy "place", seems it's not public or something? I hope J2EE compliance is close enough and the right people see it.