default EndpointGroup orElse(EndpointGroup nextEndpointGroup) {
        return new OrElseEndpointGroup(this, nextEndpointGroup);
    }
Creates a new {@link EndpointGroup} that tries this {@link EndpointGroup} first and then the specified
{@link EndpointGroup} when this {@link EndpointGroup} does not have a requested resource.

@param nextEndpointGroup the {@link EndpointGroup} to try secondly.
core/src/main/java/com/linecorp/armeria/client/endpoint/EndpointGroup.java