Relationship between fulfillmentLineItem and returnLineItem

[friend_of_root]

Ok it can be done via:

$post_data = [
    'query' => '
query getReturnLineItems($returnId: ID!) {
  return(id: $returnId) {
    returnLineItems(first: 25) {
      nodes {
        ... on ReturnLineItem {
		  id	
          refundableQuantity
          refundedQuantity
          returnReason
          returnReasonNote
          customerNote
          quantity
          fulfillmentLineItem {
            lineItem {
			  id
              name
              sku
            }
          }
        }
      }
    }
  }
}',
    'variables' => [
        'returnId' => 'gid://shopify/Return/12633145676',
    ],
];