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
this.fShownMethod = method;
        refresh();
    }
    public IMethod getMethod() {
        return fShownMethod;
    }
    public MethodWrapper getCurrentMethodWrapper() {
        if (fCurrentCallMode == CALL_MODE_CALLERS) {
            return fCallerRoot;
        } else {
            return fCalleeRoot;
        }
    }
           
    /**
     * called from ToggleOrientationAction.
     * @param orientation VIEW_ORIENTATION_HORIZONTAL or VIEW_ORIENTATION_VERTICAL
     */
    void setOrientation(int orientation) {
        if (fCurrentOrientation != orientation) {
            if ((fLocationViewer != null) && !fLocationViewer.getControl().isDisposed() &&
                        (fHierarchyLocationSplitter != null) &&
                        !fHierarchyLocationSplitter.isDisposed()) {
                if (orientation == VIEW_ORIENTATION_SINGLE) {
                    setShowCallDetails(false);
                } else {
                    if (fCurrentOrientation == VIEW_ORIENTATION_SINGLE) {
                        setShowCallDetails(true);
                    }
                    boolean horizontal = orientation == VIEW_ORIENTATION_HORIZONTAL;