How to proxy UBI images using Nexus?

Hello.
Red Hat provides UBI7 and UBI8 free images which we would like to use as base images. Our setup is complete offline so we cannot rely on availability of Red Hat registries. But we do have Nexus 3 which can proxy external repositories. Is there a detailed guide how to setup Nexus to proxy base images and some/all images built upon them, such as nodejs and openjdk-11?

Thanks.