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you can do it yourself or use plugins, but basically if you create a
couple of bridge classes to encapsulate the ones that changed.
1) do it yourself. You can use a factory pattern ... create interfaces,
return them from a factory, and then load either the 3.1 or 3.2 version
of your bridge class in the factory.
2) move your bridge classes into a small, separate plugin, and create 2
of them ... one that compiles against 3.1 and one that compiles against
3.2. Then you can set the version number so that eclipse automagically
loads the 3.1 plugin in a 3.1 install and 3.2 in a 3.2 install ... then
you can ship both plugins for deployment.