/**
  * Overlay an attribute container over the current main attribute container.
  *
  * @param container attribute container to add (overlay) to this object
  */
 private void addContainer(final AttributeContainer container) {
   this.mainContainer.addAttributes(container.getAttributes());
 }
 /**
  * @return
  * @see edu.utah.further.core.api.chain.AttributeContainer#getAttributes()
  */
 @Override
 public Map<String, Object> getAttributes() {
   return mainContainer.getAttributes();
 }