in src/main/java/org/apache/sling/hapi/client/impl/microdata/MicrodataDocument.java [177:190]
private Set<String> selectAllPropNames(Element e, Set<String> items) {
for (Element c : e.children()) {
if (c.hasAttr("itemprop")) {
items.add(c.attr("itemprop"));
}
if (c.hasAttr("itemscope")) {
continue;
}
selectAllPropNames(c, items);
}
return items;
}