BigtableConfig implements Serializable { @VisibleForTesting BigtableConfig withBigtableService(BigtableService bigtableService) { checkArgument(bigtableService != null, "bigtableService can not be null"); return toBuilder().setBigtableService(bigtableService).build(); }  @Override String toString();  }
@Test public void testWithBigtableService() { assertEquals(SERVICE, config.withBigtableService(SERVICE).getBigtableService()); thrown.expect(IllegalArgumentException.class); config.withBigtableService(null); }