src/main/java/com/theoryinpractise/halbuilder5/ResourceRepresentation.java
public ResourceRepresentation<V> withRel(Rel rel) {
    if (rels.containsKey(rel.rel())) {
      throw new IllegalStateException(String.format("Rel %s is already declared.", rel.rel()));
    }
    final TreeMap<String, Rel> updatedRels = rels.put(rel.rel(), rel);
    return new ResourceRepresentation<>(
        content, links, updatedRels, namespaceManager, value, resources);
  }
public ResourceRepresentation<V> withRel(Rel rel) {
    if (rels.containsKey(rel.rel())) {
      throw new IllegalStateException(String.format("Rel %s is already declared.", rel.rel()));
    }
    final TreeMap<String, Rel> updatedRels = rels.put(rel.rel(), rel);
    return new ResourceRepresentation<>(
        content, links, updatedRels, namespaceManager, value, resources);
  }
public ResourceRepresentation < V > withRel ( Rel rel ) { if ( rels . containsKey ( rel . rel ( ) ) ) { throw new IllegalStateException ( String . format ( "Rel %s is already declared." , rel . rel ( ) ) ) ; } final TreeMap < String , Rel > updatedRels = rels . put ( rel . rel ( ) , rel ) ; return new ResourceRepresentation <> ( content , links , updatedRels , namespaceManager , value , resources ) ; }
Define rel semantics for this representation.

@param rel A defined relationship type
Define rel semantics for this representation .