clean install

web/modules/csv_serialization/src/CsvSerializationServiceProvider.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace Drupal\csv_serialization;
+
+use Drupal\Core\DependencyInjection\ContainerBuilder;
+use Drupal\Core\DependencyInjection\ServiceModifierInterface;
+
+/**
+ * Adds 'csv' as known format.
+ */
+class CsvSerializationServiceProvider implements ServiceModifierInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function alter(ContainerBuilder $container) {
+    if ($container->has('http_middleware.negotiation') && is_a($container->getDefinition('http_middleware.negotiation')->getClass(), '\Drupal\Core\StackMiddleware\NegotiationMiddleware', TRUE)) {
+      $container->getDefinition('http_middleware.negotiation')
+        ->addMethodCall('registerFormat', ['csv', ['text/csv']]);
+    }
+  }
+
+}