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/OpenDeclarationAction.java
public OpenDeclarationAction(IWorkbenchSite site) {
        super(site);
    }
    public boolean canActionBeAdded() {
        Object element = SelectionUtil.getSingleElement(getSelection());
        IMethod method = null;
        
        if (element instanceof IMethod) {
            method = (IMethod) element;
        } else if (element instanceof IAdaptable) {
            method = (IMethod) ((IAdaptable) element).getAdapter(IMethod.class);