@NotNull
    @Override
    public DfType fromConstant(@Nullable Object obj) {
      if (obj instanceof PsiField && DfaUtil.isEmptyCollectionConstantField((PsiVariable)obj)) {
        return DfTypes.intValue(0);
      }
      return super.fromConstant(obj);
    }
@NotNull
    @Override
    public DfType fromConstant(@Nullable Object obj)