Bug 37464 call hierarchy: Should not use working copies
The call hierarchy should not use working copies of compilation units since these may go away (e.g. when an editor is closed).
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/callhierarchy/CallHierarchyViewPart.java
fCallHierarchyViewer);
        fHistoryDropDownAction = new HistoryDropDownAction(this);
        fHistoryDropDownAction.setEnabled(false);
        fToggleOrientationActions = new ToggleOrientationAction[] {
                new ToggleOrientationAction(this, VIEW_ORIENTATION_VERTICAL),
                new ToggleOrientationAction(this, VIEW_ORIENTATION_HORIZONTAL),
                new ToggleOrientationAction(this, VIEW_ORIENTATION_SINGLE)
            };
        fToggleCallModeActions = new ToggleCallModeAction[] {
                new ToggleCallModeAction(this, CALL_MODE_CALLERS),
                new ToggleCallModeAction(this, CALL_MODE_CALLEES)
            };
        fToggleImplementorsActions = new ToggleImplementorsAction[] {
                new ToggleImplementorsAction(this, IMPLEMENTORS_ENABLED),
                new ToggleImplementorsAction(this, IMPLEMENTORS_DISABLED)
            };
        fActionGroups = new CompositeActionGroup(new ActionGroup[] {
                    new OpenEditorActionGroup(getViewAdapter()), 
                    new OpenViewActionGroup(getViewAdapter()),
                    new CCPActionGroup(getViewAdapter()),
                    new GenerateActionGroup(getViewAdapter()), 
                    new RefactorActionGroup(getViewAdapter()),
                    new JavaSearchActionGroup(getViewAdapter()),
                    fSearchScopeActions, fFiltersActionGroup
                });
    }
    private CallHierarchyViewAdapter getViewAdapter() {
        if (fViewAdapter == null) {
            fViewAdapter= new CallHierarchyViewAdapter(getViewSiteAdapter());
        }