void (ULiteralExpression uLiteralExpression) { PsiElement element = uLiteralExpression.getSourcePsi(); PsiLanguageInjectionHost expression = UastLiteralUtils.getSourceInjectionHost(uLiteralExpression); if (element == null || expression == null) return; for (PsiReference reference : expression.getReferences()) { if (reference instanceof PluginConfigReference && !reference.isSoft() && reference.resolve() == null) { holder.registerProblem(reference); } } }