@Override
public void trigger(ChainReduceVertex vertex) throws IOException {
VertexMethod<String> m = methodFromConfig(vertex, findParentMethodKey, String.class);
String derivedParent = m.calculate(vertex);
Text msg = new Text("FIND_NEXT " + vertex.getId().toString());
vertex.sendMessage(new Text(derivedParent), msg);
}
void nudge(ChainReduceVertex vertex, Text target) {
if (target != null) {
vertex.sendMessage(target, new Text("_"));
}
}