String sourceKey = NodeKey.keyForSourceName(conName);
String workspaceKey = NodeKey.keyForWorkspaceName(conName);
//ask external system to determine root identifier.
ExternalDocumentStore documentStore = new ExternalDocumentStore(connectors);
String rootId = documentStore.getRootId(sourceKey);
// Compute the root key for this workspace ...
NodeKey rootKey = new NodeKey(sourceKey, workspaceKey, rootId);
// We know that this workspace is not the system workspace, so find it ...