Add support for custom arrays in XmlSeriaizer

CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - New interface `Redmine\Http\HttpClient` for new minimalistic HTTP clients.
 - New interface `Redmine\Http\Request` for sending data with new minimalistic HTTP clients.
 - New method `Redmine\Api\...::getLastResponse()` to get the last response made by the API class.
+- Add support for custom arrays in `Redmine\Serializer\XmlSerializer`
 
 ### Changed
 

src/Redmine/Serializer/XmlSerializer.php

@@ -182,6 +182,12 @@ private function addChildToXmlElement(SimpleXMLElement $xml, $k, $v): void
             foreach ($v as $id) {
                 $array->addChild($specialParams[$k], $id);
             }
+        } elseif (is_array($v)) {
+            $array = $xml->addChild($k, '');
+            $array->addAttribute('type', 'array');
+            foreach ($v as $id) {
+                $array->addChild($k, $id);
+            }
         } else {
             $xml->$k = $v;
         }

tests/Unit/Serializer/XmlSerializerTest.php

@@ -151,6 +151,25 @@ public static function getNormalizedToEncodedData(): array
                 </issue>
                 XML,
             ],
+            'test with custom array' => [
+                [
+                    'issue' => [
+                        'taglist' => [
+                            'approved',
+                            'finished',
+                        ],
+                    ],
+                ],
+                <<< XML
+                <?xml version="1.0"?>
+                <issue>
+                <taglist type="array">
+                    <taglist>approved</taglist>
+                    <taglist>finished</taglist>
+                </taglist>
+                </issue>
+                XML,
+            ],
             'test with ignored elements' => [
                 [
                     'issue' => [