ManagedChannelProvider { public static ManagedChannelProvider provider() { if (provider == null) { throw new ProviderNotFoundException("No functional channel service provider found. " + "Try adding a dependency on the grpc-okhttp or grpc-netty artifact"); } return provider; }  static ManagedChannelProvider provider();  }
@Test(expected = ManagedChannelProvider.ProviderNotFoundException.class) public void noProvider() { ManagedChannelProvider.provider(); }