Index: src/Commands/DefaultContentCommands.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- src/Commands/DefaultContentCommands.php	(date 1516621583000)
+++ src/Commands/DefaultContentCommands.php	(date 1516621583000)
@@ -57,25 +57,21 @@
    *
    * @param string $entity_type_id
    *   The entity type to export.
-   * @param int $entity_id
-   *   The ID of the entity to export.
    *
    * @command default-content:export-references
    * @option folder Folder to export to, entities are grouped by entity type into directories.
    * @aliases dcer
    */
-  public function contentExportReferences($entity_type_id, $entity_id = NULL, $options = ['folder' => NULL]) {
+  public function contentExportReferences($entity_type_id, $property_name = NULL, $property_value = NULL, $options = ['folder' => NULL]) {
     $folder = $options['folder'];
-    if (is_null($entity_id)) {
-      $entities = \Drupal::entityQuery($entity_type_id)->execute();
-    }
-    else {
-      $entities = [$entity_id];
-    }
+    $properties = $property_name ? [$property_name => $property_value] : [];
+    $entities = \Drupal::entityManager()->getStorage($entity_type_id)->loadByProperties($properties);
     // @todo Add paging.
-    foreach ($entities as $entity_id) {
-      $serialized_by_type = $this->defaultContentExporter->exportContentWithReferences($entity_type_id, $entity_id);
-      $this->defaultContentExporter->writeDefaultContent($serialized_by_type, $folder);
+    foreach ($entities as $entity) {
+      if ($entity_id = $entity->id()) {
+        $serialized_by_type = $this->defaultContentExporter->exportContentWithReferences($entity_type_id, $entity_id);
+        $this->defaultContentExporter->writeDefaultContent($serialized_by_type, $folder);
+      }
     }
   }