@Override
    public void visitThrowStatement(@NotNull PsiThrowStatement statement) {
      super.visitThrowStatement(statement);
      final PsiExpression exception =
        PsiUtil.skipParenthesizedExprDown(statement.getException());
      if (!(exception instanceof PsiLiteralExpression)) {
        return;
      }
      final PsiType type = exception.getType();
      if (!PsiTypes.nullType().equals(type)) {
        return;
      }
      registerError(exception);
    }
@Override
    public void visitThrowStatement(@NotNull PsiThrowStatement statement)