Infrastructure

RestClient holds a key-value map of headers to add to Request objects. It is inherently thread unsafe, since the RestClient instance is likely to be shared between threads. A keyword scan of CN projects shows that it is not in use, so there is little impact.

Add the @Deprecated annotation to the applicable methods, and a javadoc @deprecated comment.

For users that want more control over the HTTP requests, they should instead build an HttpRequestInterceptor and add it to the HttpClient at build time, like so:

HttpClientBuilder builder = org.dataone.client.utils.HttpUtils.getHttpClientBuilder(certificateOrTokenMaterial);
builder.addInterceptorLast(new HttpRequestInterceptor() {

 @Override
    public void process(final HttpRequest request, final HttpContext context) 
            throws HttpException, IOException 
    {
        // custom header additions here
        request.addHeader(key, value);
    }
});