private static boolean isSampled() {
        return Flags.verboseExceptionSampler().isSampled(EmptyHttpResponseException.class);
    }
Returns a {@link EmptyHttpResponseException} which may be a singleton or a new instance,
depending on {@link Flags#verboseExceptionSampler()}'s decision.
core/src/main/java/com/linecorp/armeria/common/EmptyHttpResponseException.java