public void addAttribute(GoogleBaseAttributeId attributeId,GmAttribute.Importance importance){
  if (attributeIds.contains(attributeId)) {
    throw new IllegalArgumentException("Attribute id already registered " + "in the attributes group " + attributeId);
  }
  attributes.add(new GmAttribute(attributeId,importance));
  attributeIds.add(attributeId);
}

public void addAttribute ( GoogleBaseAttributeId attributeId , GmAttribute . Importance importance ) { if ( attributeIds . contains ( attributeId ) ) { throw new IllegalArgumentException ( "Attribute id already registered " + "in the attributes group " + attributeId ) ; } attributes . add ( new GmAttribute ( attributeId , importance ) ) ; attributeIds . add ( attributeId ) ; }
adds a new attribute to the list . < p > note : the importance parameter should not be null . the current implementation allows null values for loadind old attributes persisted on client side . the null check will be enabled in a future release .
