BigtableConfig implements Serializable { BigtableConfig withProjectId(ValueProvider<String> projectId) { checkArgument(projectId != null, "Project Id of BigTable can not be null"); return toBuilder().setProjectId(projectId).build(); }  @Override String toString();  }
@Test public void testWithProjectId() { assertEquals(PROJECT_ID.get(), config.withProjectId(PROJECT_ID).getProjectId().get()); thrown.expect(IllegalArgumentException.class); config.withProjectId(null); }