ntifies the port within the node.
  Similarly, <a>GraphLinksModel.getFromKeyForLinkData</a> and <a>GraphLinksModel.getFromPortIdForLinkData</a> identify the node and its port.
</p>
<p>
  Normally a <a>GraphLinksModel</a> assumes that there is no need to recognize port information on link data.
  If you want to support port identifiers on link data, you need to set <a>GraphLinksModel.linkToPortIdProperty</a>
  and <a>GraphLinksModel.linkFromPortIdProperty</a> to be the names of the link data properties.
  If