It's a tad more verbose, but I assume the simplest way would just be to use a standard closure. void log(Supplier<? extends String> messageSupplier);

It's a tad more verbose, but I assume the simplest way would just be to use a standard closure. void log(Supplier<? extends String> messageSupplier); log(() -> log.info"User is \{someExpensiveFunction(user)}"); The pattern of using Supplier to provide a lazy argument is pretty well-established afaict.