code: public void setParentIdentifier(String parentIdentifier) {
  
          // Translate root identifier back into null
          if (parentIdentifier != null
                  && parentIdentifier.equals(RootConnectionGroup.IDENTIFIER))
              parentIdentifier = null;
  
          getModel().setParentIdentifier(parentIdentifier);
  
      }
docs: Sets the identifier of the associated parent connection group. If the
  parent is the root connection group, this should be
  RootConnectionGroup.IDENTIFIER.
  
  @param parentIdentifier
  The identifier of the connection group to associate as this object's
  parent.