code: static TrService getDelegate() {
          TrService result = delegate.get();
          if (result != null) {
              return result;
          }
  
          LogProviderConfig config = loggingConfig.get().get();
          if (config != null) {
              final TrService tr = config.getTrDelegate();
              if (tr != null) {
                  Callable<TrService> initializer = new Callable<TrService>() {
                      @Override
                      public TrService call() throws Exception {
                          return tr;
                      }
                  };
                  delegate = StaticValue.mutateStaticValue(delegate, initializer);
                  delegate.get().init(config);
                  return delegate.get();
              }
          }
  
          return DisabledDelegateSingleton.instance;
      }
docs: Package protected: retrieve the delegate (possibly creating first..).
  <ul>
  <li>If Tr has not yet been configured, the disabled delegate will be
  returned
  <li>If a delegate has been set, that instance will be returned.
  <li>Otherwise, the default delegate will be created, if necessary, and
  returned
  </ul>
  
  @return active delegate