src/main/java/org/jboss/util/graph/Graph.java
public void setRootVertex(Vertex<T> root)
   {
      this.rootVertex = root;
      if( verticies.containsValue(root) == false )
         addVertex(root);
   }
public void setRootVertex(Vertex<T> root)
   {
      this.rootVertex = root;
      if( verticies.containsValue(root) == false )
         addVertex(root);
   }
Set a root vertex. If root does no exist in the graph it is added.
@param root - the vertex to set as the root and optionally add if it
does not exist in the graph.