public static EmptyEndpointGroupException get(@Nullable EndpointGroup endpointGroup) {
        if (endpointGroup != null) {
            return new EmptyEndpointGroupException(endpointGroup);
        }
        return get();
    }
Returns an {@link EmptyEndpointGroupException} which may be a singleton or a new instance, depending on
{@link Flags#verboseExceptionSampler()}'s decision. If {@code endpointGroup} is non-null, a new
instance is always returned.
core/src/main/java/com/linecorp/armeria/client/endpoint/EmptyEndpointGroupException.java