missing option parameter/parameters in form type choice

[poolerMF]

http://symfony.com/doc/current/reference/forms/types/choice.html

missing parameter choices_as_values

and in ChoiceType.php I see another options, not described:
choice_loader
choice_label
choice_name
choice_value
choice_attr
group_by

[xabbuh]

Thank you for reporting this @poolerMF. You are absolutely right that we are currently missing docs for these things. However, we already have an issue covering this (see #5179) and two pull requests which try to cover the gap (see #5755 and #5788). That's why I am going to close here nonetheless. But anyway, once again thank you very much for your contribution!