Bug 46393 [RCP] Lost nature icon on project
N20031111 start fresh workspace, create a Java project ==> missing nature icon "J"
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/registry/MarkerImageProviderRegistry.java
public ImageDescriptor getImageDescriptor(IMarker marker) {
	int size = descriptors.size();
	for (int i = 0; i < size; i++) {
		Descriptor desc = (Descriptor)descriptors.get(i);
		try {
			if(marker.isSubtypeOf(desc.markerType)) {
				if(desc.className != null) {
					if(desc.pluginDescriptor.isPluginActivated()) {
						
						
						
						
						if(desc.provider == null)
							desc.provider = (IMarkerImageProvider)IDEWorkbenchPlugin.createExtension(
								desc.element, ATT_PROVIDER_CLASS);
						String path = desc.provider.getImagePath(marker);
						if(path != desc.imagePath) {
							desc.imagePath = path;
							desc.imageDescriptor = getImageDescriptor(desc);
							return desc.imageDescriptor;
						}
						return desc.imageDescriptor;
					} else {
						if(desc.imageDescriptor == null) {
							
							desc.imagePath = (String)marker.getAttribute(MARKER_ATT_KEY);
							desc.imageDescriptor = getImageDescriptor(desc);
						}
						return desc.imageDescriptor;
					}