Is RESTEasy RegisterBuiltin.register necessary when using ClientResponse<T> - jboss

Question

I am developing a REST client using JBOSS app server and RESTEasy 2.3.6. I've included the following line at the beginning of my code:
RegisterBuiltin.register(ResteasyProviderFactory.getInstance());
Here's the rest of the snippet:
RegisterBuiltin.register(ResteasyProviderFactory.getInstance());
DefaultHttpClient httpclient = new DefaultHttpClient();
httpclient.getCredentialsProvider().setCredentials(
new AuthScope(host, port, AuthScope.ANY_REALM), new UsernamePasswordCredentials(userid,password));
ClientExecutor executor = createAuthenticatingExecutor(httpclient, host, port);
String uriTemplate = "http://myhost:8080/webapp/rest/MySearch";
ClientRequest request = new ClientRequest(uriTemplate, executor);
request.accept("application/json").queryParameter("query", searchArg);
ClientResponse<SearchResponse> response = null;
List<MyClass> values = null;
try
{
response = request.get(SearchResponse.class);
if (response.getResponseStatus().getStatusCode() != 200)
{
throw new Exception("REST GET failed");
}
SearchResponse searchResp = response.getEntity();
values = searchResp.getValue();
}
catch (ClientResponseFailure e)
{
log.error("REST call failed", e);
}
finally
{
response.releaseConnection();
}
private ClientExecutor createAuthenticatingExecutor(DefaultHttpClient client, String server, int port)
{
// Create AuthCache instance
AuthCache authCache = new BasicAuthCache();
// Generate BASIC scheme object and add it to the local auth cache
BasicScheme basicAuth = new BasicScheme();
HttpHost targetHost = new HttpHost(server, port);
authCache.put(targetHost, basicAuth);
// Add AuthCache to the execution context
BasicHttpContext localContext = new BasicHttpContext();
localContext.setAttribute(ClientContext.AUTH_CACHE, authCache);
// Create ClientExecutor.
ApacheHttpClient4Executor executor = new ApacheHttpClient4Executor(client, localContext);
return executor;
}
The above is a fairly simple client that employs the ClientRequest/ClientResponse<T> technique. This is documented here. The above code does work (only left out some trivial variable declarations like host and port). It is unclear to me from the JBOSS documentation as to whether I need to run RegisterBuiltin.register first. If I remove the line completely - my code still functions. Do I really need to include the register method call given the approach I have taken? The Docs say I need to run this once per VM. Secondly, if I am required to call it, is it safe to call more than one time in the same VM?
NOTE: I do understand there are newer versions of RESTEasy for JBOSS, we are not there yet.