Bug 315281 update copyrights for 3.6
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/extensions/NavigatorContentDescriptorManager.java
evaluations.put(new EvalutationReference(anElement), new SoftReference(theDescriptors));
				else
					evaluationsWithOverrides.put(new EvalutationReference(anElement), new SoftReference(theDescriptors));
			}
		}
		/*
		 * (non-Javadoc)
		 * 
		 * @see org.eclipse.ui.internal.navigator.VisibilityAssistant.VisibilityListener#onVisibilityOrActivationChange()
		 */
		public void onVisibilityOrActivationChange() {
			evaluations.clear();
			evaluationsWithOverrides.clear();
		}
	}
	
	private final Map cachedTriggerPointEvaluations = new WeakHashMap();
	
	private final Map cachedPossibleChildrenEvaluations = new WeakHashMap();
	private ImageRegistry imageRegistry;
	private final Set overridingDescriptors = new HashSet();
	private final Set saveablesProviderDescriptors = new HashSet();
	private final Set sortOnlyDescriptors = new HashSet();
	private final Set firstClassDescriptorsSet = new HashSet();
	/**
	 * @return the singleton instance of the manager
	 */
	public static NavigatorContentDescriptorManager getInstance() {
		return INSTANCE;
	}