@Inject
	private IResourceDescriptions descriptions;

	@Override
	public Object execute(ExecutionEvent event) throws ExecutionException {
		for (IResourceDescription resDescription : descriptions.getAllResourceDescriptions()) {
			System.out.println(resDescription.getURI());
			for (IEObjectDescription eobjDescription : resDescription.getExportedObjects()) {
				System.out.println("    " + eobjDescription.getName() + " : " + eobjDescription.getEClass().getName());
			}
		}
		return null;
	}

@Inject
private ResourceDescriptionsProvider resourceDescriptionsProvider;

@Inject
IContainer.Manager containerManager;
...
// Some way to retrieve a resource URI. Your way may differ
URI uri = URI.createPlatformResourceURI(file.getFullPath().toString(), true);

IResourceDescriptions index = resourceDescriptionsProvider.createPersistedResourceDescriptions();
IResourceDescription resDesc = index.getResourceDescription(uri);
List<IContainer> visibleContainers = containerManager.getVisibleContainers(resDesc, index);
for (IContainer c : visibleContainers) {
    System.out.println("Container " + c.toString() + " consists of the resource descriptions:");
    for (IResourceDescription rd : c.getResourceDescriptions()) {
        System.out.println(" " + rd);
    }
    System.out.println("Container " + c.toString() + " consists of the exported objects:");
    for (IEObjectDescription eod : c.getExportedObjects()) {
        System.out.println(" " + eod.getName() + " " + eod.getEClass().getName());
    }
}