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Answered by Sergei Chevtsov, 0607-1910-2007
If your plugin has to include external JAR files as-is (e.g. due to legal issues) , it must not be jar-ed because Java class loaders can't access classes from jar-ed JAR files.
The answer above was proven wrong on 06/19/2007. Still looking for the right answer If your plugin exports packages from the included JAR files (either per your build.properties or due to legal issues), the plugin must not be jar-ed because during development of dependent plugins those packages are not visible to Eclipse's classloader. Note: this behavior can not be observed when you run your plugins.
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How does Eclipse generate the ANT build script (aka build.xml)?
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