title: Woocommerce REST API v2: Issue with adding custom data to orders
body: <p>I have a site running an old version of Woo v2.5.5 using legacy v3 for the API. I was able to use the action woocommerce_api_order_response to add data to the orders.</p>
  
  <p>Something like:</p>
  
  <pre><code>add_action( 'woocommerce_api_order_response', 'add_testing_api_function', 10, 1 );
  function add_testing_api_function( $order_data ) {
      $order_data['foo'] = "testing";
      return $order_data;
  }
  </code></pre>
  
  <p>This works fine over the older API link:</p>
  
  <p><a href="https://example.com/wc-api/v3/orders?consumer_key=KEY&amp;consumer_secret=SECRET" rel="nofollow noreferrer">https://example.com/wc-api/v3/orders?consumer_key=KEY&amp;consumer_secret=SECRET</a></p>
  
  <p>However, I need to update to Woo v3.3+ and the REST API is server up as:</p>
  
  <p><a href="https://example.com/wp-json/wc/v2/orders?consumer_key=KEY&amp;consumer_secret=SECRET" rel="nofollow noreferrer">https://example.com/wp-json/wc/v2/orders?consumer_key=KEY&amp;consumer_secret=SECRET</a></p>
  
  <p>My custom data no longer appears, and the hook does not appear to work. Is there another I can use?</p>