void (@NotNull final PsiElement element) { myHolder.registerOuterLanguageElement(element); PsiReference[] references = element.getReferences(); for (PsiReference reference : references) { if (reference instanceof PossiblePrefixReference && ((PossiblePrefixReference)reference).isPrefixReference()) { PsiElement resolve = reference.resolve(); if (resolve instanceof SchemaPrefix) { myHolder.addUsedPrefix(((SchemaPrefix)resolve).getName()); } } } }