List<String> (PsiElement element, XmlFile xmlFile) { if (element instanceof XmlAttribute) { element = element.getParent(); } Set<String> set = getXmlNamespaceHelper().guessUnboundNamespaces(element, xmlFile); final String match = getUnboundNamespaceForPrefix(myNamespacePrefix, xmlFile, set); if (match != null) { return Collections.singletonList(match); } List<String> namespaces = new ArrayList<>(set); Collections.sort(namespaces); return namespaces; }