[1.16.5] RegistryObject help

I'm trying to port a mod from forge version 40.2.1 to 36.2.39 and I'm looking for an equivalent to RegistryObject since it's absent in the older version of forge. Would also be open to a workaround, but I'm not entirely sure the best way to go about it. 

Code snippet in question:

public CustomPortalBuilder customPortalBlock(RegistryObject<CustomPortalBlock> portalBlock) {
        portalLink.setPortalBlock(portalBlock);
        return this;
    }

Also, I know this version isn't supported, but I figured someone may see it and just know. Worth a shot

Thanks!

Edited June 30, 20232 yr by stronwood