public void addCertificate(BurpCertificate burpCertificate){
  rootNode.add(new DefaultMutableTreeNode(burpCertificate));
}

public void addCertificate ( BurpCertificate burpCertificate ) { rootNode . add ( new DefaultMutableTreeNode ( burpCertificate ) ) ; }
adds a new certificate to the store directly under the root node .
