Bug 51653 [navigation] Quick Outline: Should also show interface members
I200402102000 We should consider showing the inherited members for interfaces at least when the target type is an interface itself.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/text/JavaOutlineInformationControl.java
ITypeHierarchy th= (ITypeHierarchy)fTypeHierarchies.get(type);
			if (th == null) {
				try {
					th= type.newSupertypeHierarchy(JavaPlugin.getActiveWorkbenchWindow().getActivePage().getActiveEditor().getEditorSite().getActionBars().getStatusLineManager().getProgressMonitor());
				} catch (JavaModelException e) {
					return null;
				}
				fTypeHierarchies.put(type, th);
			}
			return th;
		}
		
		/**
		 * {@inheritDoc}
		 */
		public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {
			super.inputChanged(viewer, oldInput, newInput);
			fTypeHierarchies.clear();
		}
		
		/**
		 * {@inheritDoc}
		 */
		public void dispose() {
			super.dispose();
			fTypeHierarchies.clear();
		}
	}
	/**
	 * Creates a new Java outline information control.