Похоже, вы ищете перехватчик покоя?
public class RestTemplateHeaderModifierInterceptor
implements ClientHttpRequestInterceptor {
@Override
public ClientHttpResponse intercept(
HttpRequest request,
byte[] body,
ClientHttpRequestExecution execution) throws IOException {
ClientHttpResponse response = execution.execute(request, body);
response.getHeaders().add("Foo", "bar");
return response;
}
}