Setting GWT CheckBox element id

I am trying to set an element id to GWT checkbox using flowing options, neither any of them assigning id to ckeckbox but wrapped span element.

DOM.setElementAttribute(testCheckbox.getElement(), "id", "testCheckboxId"); or

testCheckbox.getElement().setId("testCheckboxId");

compiled HTML looks like:

<span id="testCheckboxId" class="gwt-CheckBox">
   <input id="gwt-uid-328" type="checkbox" value="1" tabindex="0" checked="">
   <label for="gwt-uid-328"></label>
</span>