private static DfType getEmptyCollectionConstant(PsiMethod method) {
    String fieldName = "EMPTY_" + method.getName().substring("empty".length()).toUpperCase(Locale.ROOT);
    PsiClass collectionsClass = method.getContainingClass();
    if (collectionsClass == null) return DfType.TOP;
    PsiField field = collectionsClass.findFieldByName(fieldName, false);
    if (field == null) return DfType.TOP;
    return referenceConstant(field, field.getType());
  }
private static DfType getEmptyCollectionConstant(PsiMethod method)