title: How do can I extend woocommerce api endpoints?
body: <p>I'm trying to extend the customer endpoint in woocommerce api to include some customfields I've created in my functions.php.
  But I can't understand how to do it.</p>
  
  <p>I have copied the <code>class-wc-rest-customers-controller.php</code> from the woocommerce plugin (woocommerce/includes/api/) to my woocommerce-folder in my theme as you should do with woocommerce files when you want to edit them.</p>
  
  <p>This is how my class-wc-rest-customers-controller.php looks like:
  <a href="https://www.pastebucket.com/561405" rel="nofollow noreferrer">https://www.pastebucket.com/561405</a></p>
  
  <p>My plan now was to edit this copy of the file to include my custom_fields I've added in functions.php. But I can't solve this part.</p>
  
  <p>This is the code from my functions.php that I added my custom fields with:
  <a href="https://www.pastebucket.com/561406" rel="nofollow noreferrer">https://www.pastebucket.com/561406</a></p>
  
  <p>It feels like it is in the function at line 475 in class-wc-rest-customers-controller.php, but I'm not sure.
  So I'm wondering where and how should I add my custom fields to this <code>class-wc-rest-customers-controller.php</code> or I'm all wrong about this?</p>