public SELF withClientOptions(Function<? super ClientOptionsBuilder, ClientOptionsBuilder> configurator) {
        final ClientOptionsBuilder newBuilder =
                requireNonNull(configurator, "configurator").apply(clientOptionsBuilder);
        checkState(newBuilder != null, "configurator returned null.");
        clientOptionsBuilder = newBuilder;
        return self();
    }
Sets the {@link Function} that customizes a {@link Client} that sends health check requests.
<pre>{@code
builder.withClientOptions(b -> {
    return b.setHeader(HttpHeaders.AUTHORIZATION,
                       "bearer my-access-token")
            .responseTimeout(Duration.ofSeconds(3));
});
}</pre>
core/src/main/java/com/linecorp/armeria/client/endpoint/healthcheck/AbstractHealthCheckedEndpointGroupBuilder.java