Lravel 5.1 form - 'files' => true

I use Laravel HTML to create form but I have problem, so in creating form i have:

 {!! Form::open(['url'=>'vocuhers','files' => 'true','enctype'=>'multipart/form-data']) !!}

                @include('vouchers.form',['submitButtonText'=>'Click to Add New Vocuher'])

                {!! Form::close() !!}

but when I see my HTML form in browser therer is just:

<form method="POST" action="http://localhost:8888/vouchers" accept-charset="UTF-8"><input name="_token" type="hidden" value="dfgdfgdfgdfgdf">

so where is

enctype="multipart/form-data"

which allow me to upload files from form ?

WHy I dont get this HTML output:

<form method="POST" action="http://ift.tt/2bUcLt9" accept-charset="UTF-8" enctype="multipart/form-data"><input name="_token" type="hidden" value="dsfdfgdfgdfgdfg">

What is the problem here exactly ?

via Chebli Mohamed