<p>
  It is also common to have diagrams where you want more than one port in a node.
  The number of ports might even vary dynamically.
</p>
<p>
  In order for a link data object to distinguish which port the link should connect to,
  the <a>GraphLinksModel</a> supports two additional data properties that identify the names of the ports in the nodes
  at both ends of the link.
  <a>GraphLinksModel.getToKeyForLinkData</a> identifies the node to connect to;
  <a>GraphLinksModel.getToPortIdForLinkData</a> ide