FedEx - Add custom customs description / customer reference

functions.php

add_filter('wf_fedex_request','wf_fedex_label_request_callback', 10, 2 );
function wf_fedex_label_request_callback($request,$order){

	$custom_product_description = 'My Product Description';
	
    $request['CustomerReferences'][] =  array('CustomerReferenceType' => 'CUSTOMER_REFERENCE', 'Value' => $custom_product_description );

    $RequestedPackageLineItems = !empty( $request['RequestedShipment']['RequestedPackageLineItems'] ) ? $request['RequestedShipment']['RequestedPackageLineItems'] : array() ;
    
    $flag = 0;
    foreach ($RequestedPackageLineItems as $key => $value) {
    	$CustomerReferences = !empty($request['RequestedShipment']['RequestedPackageLineItems'][$key]['CustomerReferences']) ? $request['RequestedShipment']['RequestedPackageLineItems'][$key]['CustomerReferences'] : array();
    	foreach ($CustomerReferences as $cr_key => $cr_value) {
    		if( isset($request['RequestedShipment']['RequestedPackageLineItems'][$key]['CustomerReferences'][$cr_key]['CustomerReferenceType']) && $request['RequestedShipment']['RequestedPackageLineItems'][$key]['CustomerReferences'][$cr_key]['CustomerReferenceType'] == 'CUSTOMER_REFERENCE' ){
    			$request['RequestedShipment']['RequestedPackageLineItems'][$key]['CustomerReferences'][$cr_key]['Value'] = $custom_product_description;
    			$flag = 1;
    		}
    	}
    }
    if( $flag == 0 && !empty( $request['RequestedShipment']['RequestedPackageLineItems'][0] ) ){
    	$request['RequestedShipment']['RequestedPackageLineItems'][0]['CustomerReferences'][] =array('CustomerReferenceType' => 'CUSTOMER_REFERENCE', 'Value' => $custom_product_description );
    }
    return $request;
}