apollo-client-config-data/src/main/java/com/ctrip/framework/apollo/config/data/extension/initialize/ApolloClientPropertiesFactory.java/ApolloClientPropertiesFactory/createOauth2ClientProperties
class ApolloClientPropertiesFactory:  public OAuth2ClientProperties createOauth2ClientProperties(Binder binder,
      BindHandler bindHandler) {
    return binder.bind("spring.security.oauth2.client", Bindable.of(OAuth2ClientProperties.class),
        bindHandler).orElse(null);
  }