Custom arguments truncated to one character

[andtrev]

I'm adding custom arguments into the header, all is fine until it hits the foreach loop here: https://github.com/sendgrid/wordpress/blob/master/lib/sendgrid/class-sendgrid-translator.php#L415

As you can see it checks if there's an index, which in my case is always 0, and so it pulls the first character from the string and passes that along instead of the entire string. Should it be also checking if it's an array and isset index, else it just passes on the whole value?