Bug 287103 [CommonNavigator] contentServiceLabelProvider doesn't properly implement overrides
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/extensions/NavigatorContentDescriptor.java
* 
	 * @return True if this extension has overridding extensions.
	 */
	public boolean hasOverridingExtensions() {
		return overridingExtensions != null && overridingExtensions.size() > 0;
	}
	/**
	 * @return The set of overriding extensions (of type
	 *         {@link INavigatorContentDescriptor}
	 */
	public Set getOverriddingExtensions() {
		if (overridingExtensions == null) {
			overridingExtensions = new TreeSet(ExtensionPriorityComparator.DESCENDING);
		}
		return overridingExtensions;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see java.lang.Object#toString()
	 */
	public String toString() {
		return "Content[" + id + ", \"" + name + "\"]"; 
	}
	
	/* (non-Javadoc)
	 * @see java.lang.Object#hashCode()
	 */
	public int hashCode() {
		if (hashCode == HASH_CODE_NOT_COMPUTED) {