PSR2 MethodArgumentSpacerFixer clean additional spaces

PSR2 MethodArgumentSpacerFixer clean additional spaces after a comma.
With this code one and only one space can be after a comma in a method call.

> 4.4. Method Arguments
> In the argument list, there MUST NOT be a space before each comma, and there MUST be one space after each comma.

Thanks
Why do we need mb versoin? No test indicates that.