protected final WebClient buildWebClient() {
        final ClientOptions options = buildOptions();
        final ClientBuilderParams params = clientBuilderParams(options);
        final ClientFactory factory = options.factory();
        return (WebClient) factory.newClient(params);
    }
Returns a newly-created web client based on the properties of this builder.

@throws IllegalArgumentException if the scheme of the {@code uri} specified in
                                 {@link WebClient#builder(String)} or
                                 {@link WebClient#builder(URI)} is not an HTTP scheme
core/src/main/java/com/linecorp/armeria/client/AbstractWebClientBuilder.java