Symfony version(s) affected: 4.3.4

Description
It seems that form field has the new option row_attr. But I’m trying to use it (my version is 4.3.4 for all Sf dependencies) but I get the form error unknown option error.

The option "row_attr" does not exist. Defined options are: ........

How to reproduce

Use the row_attr option

Possible Solution

I fixed it by modifying the FormType class and add the option like done for label_attr for example.

Do I'm missing something?
I can submit a PR, if this is a real issue