protected AbstractKerberosDescriptor getRoot() {
    AbstractKerberosDescriptor root = this;

    while (root.getParent() != null) {
      root = root.getParent();
    }

    return root;
  }
Traverses up the hierarchy to find the "root" or "parent" container.
<p/>
The root AbstractKerberosDescriptor is the first descriptor in the hierarchy with a null parent.

@return the AbstractKerberosDescriptor implementation that is found to be the root of the hierarchy.
ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/AbstractKerberosDescriptor.java