Input Group Button Id

[fabionvs]

Hello guys,
I am developing using Symfony 2.8 and rendering forms using braincrafted. I am searching the best alternative to change input group button id on form type, but I couldn't find any solution.

->add('imagem', 'text', array(
'attr' => array(
'help_text' => 'Select Image.',
'input_group' => array(
'id' => 'test',
'prepend' => '.fa-image',
'button_append' => array(
'name' => 'Select Image',
'type' => 'button',
'options' => ['button_class' => 'primary', 'attr' => ['id' => 'test']]
),
)
)
))

Option 'Button Append' uses id as the same as name by default. And that is terrible!
Button HTML Output:
<button type="button" id="Select Image" name="Select Image" class="btn btn-primary">Select Image</button>

Could anyone help me to solve this problem?