code: public RunAsType<ServletType<T>> getOrCreateRunAs()
     {
        Node node = childNode.getOrCreate("run-as");
        RunAsType<ServletType<T>> runAs = new RunAsTypeImpl<ServletType<T>>(this, "run-as", childNode, node);
        return runAs;
     }
docs: If not already created, a new <code>run-as</code> element with the given value will be created.
  Otherwise, the existing <code>run-as</code> element will be returned.
  @return  a new or existing instance of <code>RunAsType<ServletType<T>></code>