private Node findNodeById(String id) {
		for (Node n : nodes) {
			if (n.id.equals(id)) {
				return n;
			}
		}
		return null;
	}
Walk a specified link to see if it ever hits the candidate node.

@param link points to the head of a chain of nodes
@param candidate the node possibly found on the chain of nodes
@return true if the candidate is found down the specified chain
spring-xd-dirt/src/main/java/org/springframework/xd/dirt/job/dsl/Graph.java