code: private void startElementMixin(final Attributes attributes) {
  
          LOG.debug("Found mixin declaration");
          try {
              this.addMixin(this.nodeStack.peek(), attributes);
          } catch (final RepositoryException e) {
              throw new AssertionError("Could not add mixin type", e);
          }
      }
docs: Invoked on mixin element.
  
  @param attributes
  the DOM attributes of the mixin element
  
  @throws SAXException
  if the mixin type can not be added