@Nullable
    private static List<StackFrameItem> extract(@NotNull Map<ReferenceType, Map<ObjectReference, List<StackFrameItem>>> map,
                                                @NotNull ObjectReference ref) {
      final Map<ObjectReference, List<StackFrameItem>> ref2Stack = map.get(ref.referenceType());
      return ref2Stack != null ? ref2Stack.get(ref) : null;
    }
@Nullable
    private static List<StackFrameItem> extract(@NotNull Map<ReferenceType, Map<ObjectReference, List<StackFrameItem>>> map,
                                                @NotNull ObjectReference ref)