java.lang.NoClassDefFoundError: org/eclipse/core/resources/ResourcesPlugin
if you create a Debug configuration from your product file, in my case CDOServer.product, then
1. you go an select the Plug-ins tab in the Debug Configuration
2. then click "Add Required plug-ins"
it may build a dependency that just does not work.
It seems you have do step 1 above, then
2. "Deselect All"
3. Select your own package
4. Click "Add Required plug-ins" a few times until the number of required plugins stop increasing, see the display "x out of y selected"
ref : Eclipse