multiple property is not supported ?

[amrography]

I don't get the input html tag with multiple property

This is my code:

<div class="btn btn-danger btn-block btn-upload" upload-button url="/php/up.php?{{params}}" param="images" data="formData" multiple="true" required="true" on-upload="function1()" on-success="function2(response)" on-error="function3(response)">
   <h5>اختر الصور</h5>
</div>

This is what I get:
<input type="file" required="required">