@NotNull
    public Set<Object> getExpressionValues(@Nullable PsiExpression expression) {
      if (expression == null) return Collections.emptySet();
      DataflowPoint point = myData.get(new JavaExpressionAnchor(expression));
      if (point == null) return Collections.emptySet();
      Set<Object> values = point.myPossibleValues;
      return values == null ? Collections.emptySet() : Collections.unmodifiableSet(values);
    }
@NotNull
    public Set<Object> getExpressionValues(@Nullable PsiExpression expression)