code: public <T> T getService(String serviceName) {
      T service = findService(serviceName, true);
      if (service == null) {
        throw new IllegalArgumentException(format("No service found named \"%s\"", serviceName));
      }
  
      return service;
    }
docs: Returns the service associated with the given name.
  
  @throws IllegalArgumentException if no such service can be found
  @throws IllegalStateException if this scope is dead
  @see #hasService