code: protected void setHeadersByAuthorizationPolicy(
              Message message,
              URI currentURI
      ) {
          Headers headers = new Headers(message);
          AuthorizationPolicy effectiveAuthPolicy = getEffectiveAuthPolicy(message);
          String authString = authSupplier.getAuthorization(effectiveAuthPolicy, currentURI, message, null);
          if (authString != null) {
              headers.setAuthorization(authString);
          }
  
          String proxyAuthString = proxyAuthSupplier.getAuthorization(proxyAuthorizationPolicy,
                                                                 currentURI, message, null);
          if (proxyAuthString != null) {
              headers.setProxyAuthorization(proxyAuthString);
          }
      }
docs: This call places HTTP Header strings into the headers that are relevant
  to the Authorization policies that are set on this conduit by
  configuration.
  <p>
  An AuthorizationPolicy may also be set on the message. If so, those
  policies are merged. A user name or password set on the messsage
  overrides settings in the AuthorizationPolicy is retrieved from the
  configuration.
  <p>
  The precedence is as follows:
  1. AuthorizationPolicy that is set on the Message, if exists.
  2. Authorization from AuthSupplier, if exists.
  3. AuthorizationPolicy set/configured for conduit.
  
  REVISIT: Since the AuthorizationPolicy is set on the message by class, then
  how does one override the ProxyAuthorizationPolicy which is the same
  type?
  
  @param message
  @param currentURI