@SuppressWarnings("unchecked")
    public final T newTokenConsumer(Consumer<? super GrantedOAuth2AccessToken> newTokenConsumer) {
        delegate.newTokenConsumer(requireNonNull(newTokenConsumer, "newTokenConsumer"));
        return (T) this;
    }
An optional hook which gets executed whenever a new token is issued.

<p>This can be used in combination with {@link #fallbackTokenProvider(Supplier)} to store a newly issued
access token which will then be retrieved by invoking the fallback token provider.
oauth2/src/main/java/com/linecorp/armeria/client/auth/oauth2/AbstractOAuth2AuthorizationGrantBuilder.java