code: public static Set<String> namesOf(AdminsConfig adminsConfig, Map<String, Collection<String>> rolesToUsers) {
          List<AdminUser> admins = adminsConfig.getUsers();
          Set<String> adminNames = new HashSet<>();
  
          for (AdminUser admin : admins) {
              adminNames.add(admin.getName().toLower());
          }
  
          for (AdminRole adminRole : adminsConfig.getRoles()) {
              adminNames.addAll(emptyIfNull(rolesToUsers.get(adminRole.getName().toLower())));
          }
  
          return adminNames;
      }
docs: Compiles a list of users from an {@link AdminsConfig}, denormalizing roles to the underlying
  members.
  
  @param adminsConfig the config fragment
  @param rolesToUsers a {@link Map} of member users to their respective roles
  @return a {@link Set} of user names from the config