This is my first patch to JRuby, so please be teach me where I'm wrong.
I noticed Struct.members return an Array of Strings, even in 1.9.
A patch is attached, it removes the RubySpec tag which was "hiding" this issue.
I'm unsure if the duplication between members18 and members19 is fine, but as it is mostly a loop, it's probably fine.
I used the members18 method in unmarshalFrom(), maybe using the 19 version would be faster since it does not require to convert members to ruby Strings?
Hope it helps,