String (List<? extends PsiElement> elements, @Nullable Editor editor) { if (elements.isEmpty()) return null; List<String> fqns = new ArrayList<>(); for (PsiElement element : elements) { String fqn = elementToFqn(element, editor); if (fqn == null) return null; fqns.add(fqn); } return StringUtil.join(fqns, "\n"); }