code: public <U extends ODataEntity<?>> LinkInfo<U> getRelationLink(
              String relationName) {
          return this.<U> getLink(Constants.ODATA_DATA_NS + "/related/"
                  + relationName);
      }
docs: Get the link to navigate an OData relationship
  
  @param relationName
  name of the OData relationship
  @return the link if found, null if not.