title: Select2 multi select blank option always selected
body: <p>I am using select2 for multi select and when I select first time , any option , null value from blank option always get selected.
  And another problem if I don't use placeholder first option get selected when loaded. </p>
  
  <p>Here is my code for html(it includes some php):</p>
  
  <pre><code>&lt;select class="form-control select2-multiple" name="category_id"&gt;
          &lt;option&gt;&lt;/option&gt;
          @foreach($instrument_category as $key=&gt;$value)
              &lt;option value="{{ $value }}"&gt;{{ $value }}&lt;/option&gt;
          @endforeach
  &lt;/select&gt;
  </code></pre>
  
  <p>here is my jquery:</p>
  
  <pre><code>$(".select2-multiple").select2({
      'placeholder' : "Select Category",
      'multiple' : true,
      'defaultView': 'dropdown'
  });
  </code></pre>
  
  <p>Again problem : blank value get selected when selected for first time.</p>
  
  <p>Screenshot given.</p>
  
  <p><a href="https://i.stack.imgur.com/56J1E.png" rel="noreferrer"><img src="https://i.stack.imgur.com/56J1E.png" alt="blank value selected"></a></p>