How to pass options to CustomType in `collection` field Symfony 2.1?

Question

I have SuperType Form for Entity Super.

In this form I have a collection field of ChildType Form types for Entity

Answer 1

In Symfony 3, this is called entry_options.

$builder->add('childrens', CollectionType::class, array(
    'entry_type'   => ChildType::class,
    'entry_options'  => array(
        'my_custom_option'  => true
    ),
));