Fixes #257 by add request options

migrate_example_advanced/config/install/migrate_plus.migration.wine_variety_multi_xml.yml

@@ -9,6 +9,9 @@ source:
   plugin: url
   data_fetcher_plugin: http
   data_parser_plugin: xml
+  # Guzzle request options can be added.
+  request_options:
+    allow_redirects: false
   # Normally, this is one or more fully-qualified URLs or file paths. Because
   # we can't hardcode your local URL, we provide a relative path here which
   # hook_install() will rewrite to a full URL for the current site.

src/Plugin/migrate_plus/data_fetcher/Http.php

@@ -99,6 +99,9 @@ class Http extends DataFetcherPluginBase implements ContainerFactoryPluginInterf
       if (!empty($this->configuration['authentication'])) {
         $options = array_merge($options, $this->getAuthenticationPlugin()->getAuthenticationOptions());
       }
+      if (!empty($this->configuration['request_options'])) {
+        $options = array_merge($options, $this->configuration['request_options']);
+      }
       $response = $this->httpClient->get($url, $options);
       if (empty($response)) {
         throw new MigrateException('No response at ' . $url . '.');