Jersey 2.x add multiple headers to ClientConfig

Question

I've looked at different answers on here and they're all about adding header(s) during a request call. I would like to add headers in the client config then register it with the client itself.

I've looked around and found that I can create a custom ClientRequestFilter, but looking at the add() method signatures, I don't see any in which I can add multiple headers - they all take like a string as the first argument, then like a list.

For example, I would like to add these headers:

Accept: 'something'
Client-ID: 'another something'
Authorization: 'OAuth more something'

I came up with the code below, but it seems only the first register() method call is actually used. I checked the debugger and all I see is the first Accept header and the User-Agent header added by Jersey.

public OAuth2Authenticator(String header, String value) {
    this.header = header;
    this.value = value;
}

@Override
public void filter(ClientRequestContext requestContext) throws IOException {
    requestContext.getHeaders().add(header, value);
}


...

client = ClientBuilder.newClient(new ClientConfig());
client.register(new OAuth2Authenticator(HttpHeaders.ACCEPT, API_VERSION))
      .register(new OAuth2Authenticator("Client-ID", clientId))
      .register(new OAuth2Authenticator(HttpHeaders.AUTHORIZATION, "OAuth " + accessToken));

Answer 1

I was able to get it to work by assigning to a MultivalueMap first, then calling add().

MultivaluedMap<String, Object> headers = requestContext.getHeaders();
headers.add(HttpHeaders.ACCEPT, "something");
headers.add("Client-ID", another something);
headers.add(HttpHeaders.AUTHORIZATION, "OAuth more something");

...

client = ClientBuilder.newClient(new ClientConfig());
client.register(new OAuth2Authenticator( API_VERSION, clientId, accessToken));