List<DomElementProblemDescriptor> (final DomElement element, final DomElementAnnotationHolder holder) { List<DomElementProblemDescriptor> result = null; for (DomCustomAnnotationChecker<?> checker : DomCustomAnnotationChecker.EP_NAME.getExtensionList()) { final List<DomElementProblemDescriptor> list = checkAnno(element, checker, holder); if (!list.isEmpty()) { if (result == null) result = new SmartList<>(); result.addAll(list); } } return result == null ? Collections.emptyList() : result; }