Bug 274236 [CommonNavigator] Incorrect check for existence of item in contribution memory
The check in the NavigatorContentService.rememberContribution() should be containsKey(), not containsValue()
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/NavigatorContentService.java
import org.eclipse.ui.navigator.IExtensionActivationListener;
import org.eclipse.ui.navigator.IExtensionStateModel;
import org.eclipse.ui.navigator.IMementoAware;
import org.eclipse.ui.navigator.INavigatorActivationService;
import org.eclipse.ui.navigator.INavigatorContentDescriptor;
import org.eclipse.ui.navigator.INavigatorContentExtension;
import org.eclipse.ui.navigator.INavigatorContentService;
import org.eclipse.ui.navigator.INavigatorContentServiceListener;
import org.eclipse.ui.navigator.INavigatorDnDService;
import org.eclipse.ui.navigator.INavigatorFilterService;
import org.eclipse.ui.navigator.INavigatorPipelineService;
import org.eclipse.ui.navigator.INavigatorSaveablesService;
import org.eclipse.ui.navigator.INavigatorSorterService;
import org.eclipse.ui.navigator.INavigatorViewerDescriptor;
import org.osgi.service.prefs.BackingStoreException;
/**
 * <p>
 * Provides centralized access to the information provided by
 * NavigatorContentExtensions. Can be instantiated as needed, but should be
 * cached for active viewers. Information specific to a given viewer will be
 * cached by the NavigatorContentService, not including ContentProviders and
 * Label Providers created by {@link #createCommonContentProvider()}and
 * {@link #createCommonLabelProvider()}respectively.
 * </p>
 * 
 * <p>
 * The following class is experimental until fully documented.
 * </p>
 */
public class NavigatorContentService implements IExtensionActivationListener,