I'm sorry, I should have been more clear, I did remove the jars as suggested, which fixes the call to prefs.exportSubtree(System.out) - but if I then try to call DocumentBuilderFactory.newInstance(), it will fail with the following exception:
Caught: javax.xml.parsers.FactoryConfigurationError: Provider for javax.xml.parsers.DocumentBuilderFactory cannot be found
...which happens because the jars have been removed. Setting the system property for javax.xml.parsers.DocumentBuilderFactory to anything other than the included xerces parser seems to cause a ClassCastException.
I did manage to find a workaround though that allows me to continue working with Groovy 1.0 that only requires a small code workaround, which is as follows:
1. Do not remove any of the files from the groovy-1.0/lib directory.
2. Before calling any of the methods of the Preferences class that deal with xml (Preferences.exportSubtree() or Preferences.importPreferences for example... This may also apply to other standard Java API classes that use xml) use:
...to bypass the xml parser included in Groovy. Once finished with the offending calls, use:
...to reset the parser factory back to its original setting.
This workaround allows me to continue to use Groovy 1.0 (and hence the eclipse plugin) so as far as I'm concerned the issue is closed, but I will leave it open in the issue tracker in case you have further comments on it. Feel free to close it if you don't. I did notice that Guillaume Laforge changed the fixed version from 1.1-beta2 to rc1, I just thought I should mention that I have tested it under beta 2 and my code did work, but I haven't tested it under rc1 at all.
Thank you for your input in helping me solve this problem.