commit 8572770717ce5696ed1da7924ca803b35da2a253
Author: Randy Fay <randy@randyfay.com>
Date:   Fri May 6 17:44:48 2011 -0600

    First attempt at a fix

diff --git a/modules/line_item/commerce_line_item.info.inc b/modules/line_item/commerce_line_item.info.inc
index aa170dc..83e1619 100644
--- a/modules/line_item/commerce_line_item.info.inc
+++ b/modules/line_item/commerce_line_item.info.inc
@@ -38,6 +38,37 @@ function commerce_line_item_entity_property_info() {
     'required' => TRUE,
     'clear' => array('order_id'),
   );
+  $properties['commerce_product'] = array(
+    'label' => t('Product', array(), array('context' => 'a product associated with this line item')),
+    'type' => 'commerce_product',
+    'field' => TRUE,
+    'description' => t('The product on this line item.'),
+    'getter callback' => 'commerce_line_item_get_properties',
+    'setter callback' => 'commerce_line_item_set_properties',
+    'setter permission' => 'administer line items',
+    'required' => TRUE,
+  );
+  $properties['commerce_unit_price'] = array(
+    'label' => t('Unit price', array(), array('context' => 'the unit price of this line item')),
+    'type' => 'commerce_price',
+    'field' => TRUE,
+    'description' => t('The unit price of this line item.'),
+    'getter callback' => 'commerce_line_item_get_properties',
+    'setter callback' => 'commerce_line_item_set_properties',
+    'setter permission' => 'administer line items',
+    'required' => TRUE,
+  );
+  $properties['commerce_display_path'] = array(
+    'label' => t('Display Path', array(), array('context' => 'the display path')),
+    'type' => 'commerce_display_path',
+    'field' => TRUE,
+    'description' => t('The display path.'),
+    'getter callback' => 'commerce_line_item_get_properties',
+    'setter callback' => 'commerce_line_item_set_properties',
+    'setter permission' => 'administer line items',
+    'required' => TRUE,
+  );
+
   $properties['type'] = array(
     'label' => t('Type'),
     'description' => t('The human readable name of the line item type.'),
diff --git a/modules/product_reference/commerce_product_reference.module b/modules/product_reference/commerce_product_reference.module
index 796bd9f..2fe5a25 100644
--- a/modules/product_reference/commerce_product_reference.module
+++ b/modules/product_reference/commerce_product_reference.module
@@ -841,7 +841,7 @@ function commerce_product_line_item_populate($line_item, $product, $display_uri
     $line_item->data['display_uri'] = $display_uri;
   }
   else {
-    $line_item_wrapper->commerce_display_path = '';
+    $line_item_wrapper->commerce_display_path = array();
     $line_item->data['display_uri'] = NULL;
   }