code: public static Node getChildNode(Node parentNode, String name, String value){
                  List<Node> matchingChildren = getChildren(parentNode, name, value);
                  return (matchingChildren.size() > 0) ? matchingChildren.get(0) : null;
          }
docs: Get the matching child node
  @param parentNode - the parent node
  @param name - name of child node to match
  @param value - value of child node to match, specify null to not match value
  @return the child node if a match was found, null otherwise