Does anybody know how to add the remove button in a custom module (field type) with unlimited number of values? I am trying to add my custom field/module to a content type. I select Unlimited for the Allowed number of values option in Field Settings and I am able to Add another Item, however there is no remove button. Furthermore, each time I edit the content; an extra (blank) field is added.
The custom field type has to implement a method which tells whether the field is empty (if the inherited default method is not able to do this).

For example for a numeric field:

NumericItemBase::isEmpty()

  public function isEmpty() {
    if (empty($this-&gt;value) &amp;&amp; (string) $this-&gt;value !== '0') {
      return TRUE;
    }
    return FALSE;
  }