Bug 126658 [CommonNavigator] [DND] Complete definition of DND API
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/navigator/CommonDropAdapterAssistant.java
* assistant returns true, the assist must
 * {@link #handleDrop(DropTargetEvent, Object) }. If multiple assistants match
 * the drop target, then the potential assistants are ordered based on priority
 * and their override relationships and given an opportunity to validate the
 * drop operation in turn. The first one to validate will have the opportunty to
 * carry out the drop.
 * </p>
 * <p>
 * That is, if a content extension X overrides content extension Y (see
 * <b>org.eclipse.ui.navigator.navigatorContent/override</b>), then X will have
 * an opportunity before Y. If X and Y override Z, but X has higher priority
 * than Y, then X will have an opportunity before Y, and Y will have an
 * opportunity before Z.
 * </p>
 * <p>
 * <strong>EXPERIMENTAL</strong>. This class or interface has been added as
 * part of a work in progress. There is a guarantee neither that this API will
 * work nor that it will remain the same. Please do not use this API without
 * consulting with the Platform/UI team.
 * </p>
 * <p>
 * Clients may implement this interface.
 * </p>
 * 
 * @see INavigatorDnDService
 * @see INavigatorDnDService#findCommonDropAdapterAssistants(Object)
 * @since 3.2
 * 
 */
public abstract class CommonDropAdapterAssistant {