The plug-in exporter uses the same mechanism for creating the p2
structure as the feature/product exporter. Therefore, it also loads all
features available in the classpath.

If one of those features happens to be a workspace resource, meaning it
lacks an install location, the exporter will always fail with a
NullPointerException, even if the feature is not referenced by the
selected items and therefore not relevant for the current task.

Instead, those features should be skipped. If those features are
referenced by the exported items, the Eclipse will open an error dialog,
informing the user about the missing item. It is then the responsibility
of the development team providing those features to ensure that the
install location is set.

Example: Synthetic features derived from Maven poms via m2e.