nk20/templates/bootstrap_datepicker_plus/input.html

<input type="{{ widget.type }}" name="{{ widget.name }}"{% if widget.value != None and widget.value != "" %}
       value="{{ widget.value }}"{% endif %}{% for name, value in widget.attrs.items %}{% ifnotequal value False %}
    {{ name }}{% ifnotequal value True %}="{{ value|stringformat:'s' }}"{% endifnotequal %}
{% endifnotequal %}{% endfor %}/>