title: It is possible that attributeChangedCallback get a object an object like a newVal?
body: <p>I'd problem when I set a object y a property in webcomponents. In my code it's listening change in a property with <code>attributeChangedCallback(attrName, oldVal, newVal)</code> but when I receive a new property the value of newVal is equal to <code>[Object object]</code>. Why is it happening?</p>
  
  <p>Thanks</p>