Bug 126658 [CommonNavigator] [DND] Complete definition of DND API
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/navigator/INavigatorContentDescriptor.java
/**
	 * @return Returns the suppressedExtensionId or null if none specified.
	 */
	String getSuppressedExtensionId();
	/**
	 * @return Returns the overridePolicy or null if this extension does not
	 *         override another extension.
	 */
	OverridePolicy getOverridePolicy();
	
	/**
	 * @return The descriptor of the <code>suppressedExtensionId</code> if non-null.
	 */
	INavigatorContentDescriptor getOverriddenDescriptor();
	
	/**
	 * 
	 * Does not force the creation of the set of overriding extensions.
	 * 
	 * @return True if this extension has overridding extensions.
	 */
	boolean hasOverridingExtensions();
	
	/**
	 * @return The set of overridding extensions (of type
	 *         {@link INavigatorContentDescriptor}
	 */
	Set getOverriddingExtensions();
	
}