code: @Override
      public void addLink(String name1, String name2, String... domain) {
          if (domain.length == 1) {
              name1 = domain[0] + "::" + name1;
              name2 = domain[0] + "::" + name2;
          } else if (domain.length > 1) {
              throw new Error("error: domain should be 1 parameter");
          }
  
          Role role1 = createRole(name1);
          Role role2 = createRole(name2);
          role1.addRole(role2);
      }
docs: addLink adds the inheritance link between role: name1 and role: name2.
  aka role: name1 inherits role: name2.
  domain is a prefix to the roles.