spring-hateoas-ext/src/main/java/de/escalon/hypermedia/affordance/Affordance.java
public void addLinkParam(String paramName, String... values) {
        Assert.notEmpty(values);
        for (String value : values) {
            Assert.hasLength(value);
            linkParams.add(paramName, value);
        }
    }
public void addLinkParam(String paramName, String... values) {
        Assert.notEmpty(values);
        for (String value : values) {
            Assert.hasLength(value);
            linkParams.add(paramName, value);
        }
    }
Adds link-extension params, i.e. custom params which are not described in the web linking rfc.

@param paramName of link-extension
@param values    one or more values to add