/**
* Utility method to group child nodes by their names.
*
* @param parent parent node.
* @return Map from name to child nodes.
*/
private static Map<String, List<Node>> getChildNodes(Node parent) {
if (parent == null) return Collections.emptyMap();
Map<String, List<Node>> children = new HashMap<String, List<Node>>();
NodeList nodes = parent.getChildNodes();
int nNodes = nodes.getLength();
for (int i = 0; i < nNodes; i++) {
Node node = nodes.item(i);
if (node.getNodeType() != Node.ELEMENT_NODE) continue;
String name = node.getNodeName();
List<Node> namesakes = children.get(name);
if (namesakes == null) {
namesakes = new ArrayList<Node>();
children.put(name, namesakes);
}
namesakes.add(node);
}
return children;
}
