public static @NlsContexts.DetailedDescription String checkInterfaceFunctional(@NotNull PsiClass psiClass) {
    return checkInterfaceFunctional(psiClass, JavaErrorBundle.message("target.type.of.a.lambda.conversion.must.be.an.interface"));
  }
public static @NlsContexts.DetailedDescription String checkInterfaceFunctional(@NotNull PsiClass psiClass)