private Map<String, Collection<String>> toMap(MultivaluedMap<String, String> headers) {
    return headers.entrySet().stream().collect(Collectors.toMap(Entry::getKey, Entry::getValue));
  }
This module directs Feign's http requests to javax.ws.rs.client.Client . Ex:

<pre>
GitHub github =
    Feign.builder().client(new JaxRSClient()).target(GitHub.class, "https://api.github.com");
</pre>
jaxrs2/src/main/java/feign/jaxrs2/JAXRSClient.java