Bug 46351 Call Hierarchy must not implement IViewSite [call hierarchy]
I20031105 The call hierarchy component implements IViewSite which is not allowed. There seems to be no reason for doing so: the CallHierarchyViewPart should directly set the selection provider to its site.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/callhierarchy/FocusOnSelectionAction.java
private CallHierarchyViewPart fPart;
    public FocusOnSelectionAction(CallHierarchyViewPart part) {
        super(CallHierarchyMessages.getString("FocusOnSelectionAction.focusOnSelection.text")); 
        fPart= part;
        setDescription(CallHierarchyMessages.getString("FocusOnSelectionAction.focusOnSelection.description")); 
        setToolTipText(CallHierarchyMessages.getString("FocusOnSelectionAction.focusOnSelection.tooltip")); 
        WorkbenchHelp.setHelp(this, IJavaHelpContextIds.CALL_HIERARCHY_FOCUS_ON_SELECTION_ACTION);
    }
    public boolean canActionBeAdded() {
        Object element = SelectionUtil.getSingleElement(getSelection());
        IMethod method = null;
        
        if (element instanceof IMethod) {
            method= (IMethod) element;
        } else if (element instanceof MethodWrapper) {
            IMember member= ((MethodWrapper) element).getMember();
            if (member.getElementType() == IJavaElement.METHOD) {