spring-hateoas-ext/src/main/java/de/escalon/hypermedia/affordance/Affordance.java
public void addRel(String rel) {
        Assert.hasLength(rel);
        linkParams.add(REL.paramName, rel);
    }
public void addRel(String rel) {
        Assert.hasLength(rel);
        linkParams.add(REL.paramName, rel);
    }
The relation type of the link.

@param rel IANA-registered type or extension relation type.