IntentionPreviewInfo (@NotNull Project project, PsiElement element, @Nullable Editor editor) { PsiFile file = element.getContainingFile(); if (!(file instanceof XmlFile xmlFile)) return IntentionPreviewInfo.EMPTY; List<String> namespaces = getNamespaces(element, xmlFile); String namespace = namespaces.isEmpty() ? "" : namespaces.get(0); new MyStringToAttributeProcessor(element, project, editor, xmlFile) .doSomethingWithGivenStringToProduceXmlAttributeNowPlease(namespace); return IntentionPreviewInfo.DIFF; }