Dcat-Admin/resources/views/form/multipleselect.blade.php

<div class="{{$viewClass['form-group']}} {!! !$errors->has($errorKey) ? '' : 'has-error' !!}">

    <div for="{{ $id }}" class="{{$viewClass['label']}} control-label">
        <span>{!! $label !!}</span>
    </div>

    <div class="{{$viewClass['field']}}">

        @include('admin::form.error')

        <select class="form-control {{$class}}" style="width: 100%!important;" name="{{$name}}[]" multiple="multiple" data-placeholder="{{ $placeholder }}" {!! $attributes !!} >
            @foreach($options as $select => $option)
                <option value="{{$select}}" {{  in_array($select, (array)old($column, $value)) ?'selected':'' }}>{{$option}}</option>
            @endforeach
        </select>
        <input type="hidden" name="{{$name}}[]" />

        @include('admin::form.help-block')

    </div>
</div>